WO2018121111A1

WO2018121111A1 - Method and device for eliminating local oscillation leakage

Info

Publication number: WO2018121111A1
Application number: PCT/CN2017/111020
Authority: WO
Inventors: 熊林江; 曲玉周; 马兴望; 陈豪; 林洁
Original assignee: 中兴通讯股份有限公司
Priority date: 2016-12-26
Filing date: 2017-11-15
Publication date: 2018-07-05
Also published as: CN108242940A

Abstract

The invention relates to the field of mobile communication, and specifically, to a method and device for eliminating local oscillation (LO) leakage. The device for eliminating LO leakage comprises: a coupler used to perform an LO leakage signal extraction process on an up-conversion signal or a down-conversion signal output by a mixer to obtain an LO leakage signal; an amplitude detection and adjustment module used to adjust, according to an amplitude of the LO leakage signal, an amplitude of an LO signal to obtain an LO leakage amplitude cancellation signal equal to the amplitude of the LO leakage signal; and a phase detection and adjustment module used to adjust, according to a phase of the LO leakage signal, a phase of the LO leakage amplitude cancellation signal to obtain a LO leakage cancellation signal having a same amplitude as the LO leakage signal and being 180 degrees out of phase of the LO leakage signal.

Description

Device and method for eliminating local oscillator leakage

Technical field

The present disclosure relates to the field of mobile communication technologies, and in particular, to an apparatus and method for eliminating local oscillator leakage.

Background technique

With the development of wireless communication technology, mobile communication has almost occupied the market in the communication field, including people, people and things, things and things, and the Internet of Everything has become an inevitable trend. The frequency of commonly used wireless communication signals ranges from a few hundred megahertz to several gigahertz. Due to the limited spectrum resources in the low frequency band, the spectrum of future wireless communication signals is likely to be higher. Since the application of current RF sampling is limited by the device, the core of the current wireless communication is to convert the RF signal in the air into a baseband signal that the digital device can process, that is, frequency conversion processing.

The frequency conversion is realized by mixing, the baseband signal and the local oscillator signal are mixed to generate the radio frequency signal, that is, the up-conversion, and the radio frequency signal and the local oscillator signal are mixed to generate the baseband signal, that is, down-converting. In the process of up-and down-conversion, since the mixer is not an ideal device, the local oscillator signal will leak into the RF signal or the baseband signal. In particular, due to limited spectrum resources, it is inevitable that a device contains several frequency bands and different types of signals. It is very common that the local oscillator leakage signal of one transmitting channel affects the signal of another transmitting channel. These local oscillator leakage signals reduce the signal-to-noise ratio of the signal, cause a large error rate, and affect the communication quality.

Therefore, when designing the transceiver, it is necessary to consider the local oscillator leakage problem and eliminate the local oscillator leakage in the design. The traditional method has two directions. One is to add a filter at the output to suppress the local oscillator leakage. This method is relatively simple, and has higher requirements on the flatness and suppression of the filter. In the near future, in order to avoid interference between the two channels, the transition sections of the passband and the stopband of the filters of the two channels are made very steep, close to the ideal filter, which is very difficult to implement in practical applications; Another direction is to detect the leakage of the local oscillator at the end of the transceiver link. After amplification, comparison, and counting, the digital signal is converted into a digital signal, and the corresponding algorithm is used to control the baseband signal to cancel the local oscillator leakage. This method needs to have the following shortcomings point:

(1) Requires the relevant hardware of the detector, amplifier, comparator, ADC, processor, etc.;

(2) It is necessary to develop a set of algorithms dedicated to eliminating local oscillator leakage, consuming processor resources;

(3) The real-time performance is not strong, and the analog-to-digital conversion and program algorithms all have to be time-consuming to complete.

(4) This method has a large link complexity, and the hardware and software cost are large, which is not suitable for general commercial use.

Summary of the invention

Embodiments of the present disclosure provide a solution for eliminating local oscillator leakage, which can solve the problem of local oscillator leakage in communication and test equipment.

An apparatus for eliminating local oscillator leakage according to an embodiment of the present disclosure includes:

a coupler for performing a local oscillator leakage signal extraction process on the upconverted signal or the downconverted signal output from the mixer to obtain a local oscillator leakage signal;

An amplitude detecting and adjusting module, configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal, to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal;

The phase detection and adjustment module is configured to perform phase adjustment on the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, to obtain a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.

In an embodiment of the present disclosure, the amplitude detection and adjustment module includes:

An amplitude detecting unit configured to perform amplitude analysis on the local oscillator leakage signal to obtain an amplitude of the local oscillator leakage signal;

And an amplitude adjustment unit configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillation leakage signal to obtain a local oscillation leakage amplitude cancellation signal equal to the amplitude of the local oscillation leakage signal.

In an embodiment of the present disclosure, the phase detection and adjustment module includes:

a phase detecting unit configured to perform phase analysis on the local oscillator leakage signal to obtain a local oscillation The phase of the leakage signal;

The phase adjustment unit is configured to perform phase adjustment on the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, to obtain a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.

A method for eliminating local oscillator leakage according to an embodiment of the present disclosure includes:

The local oscillator leakage signal is obtained by performing a local oscillator leakage signal extraction process on the up-converted signal or the down-converted signal output from the mixer;

Performing amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal;

Phase-adjusting the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtaining a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.

In an embodiment of the present disclosure, the amplitude adjustment of the local oscillation signal according to the amplitude of the local oscillation leakage signal, and obtaining a local oscillation leakage amplitude cancellation signal equal to the amplitude of the local oscillation leakage signal includes:

Performing amplitude analysis on the local oscillator leakage signal to obtain the amplitude of the local oscillator leakage signal;

The amplitude of the local oscillator signal is adjusted according to the amplitude of the local oscillator leakage signal to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal.

In an embodiment of the present disclosure, the phase adjustment of the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtaining the local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal includes:

Phase analysis of the local oscillator leakage signal to obtain a phase of the local oscillator leakage signal;

a signal output module, configured to output an up-converted signal or a down-converted signal including a local oscillator leakage signal;

Obtaining a local oscillation leakage cancellation signal module, configured to obtain an amplitude and a phase of a local oscillation leakage signal from the up-converted signal or the down-converted signal, and perform amplitude and phase on the local oscillation signal according to the amplitude and phase of the local oscillation leakage signal Adjusting to obtain a local oscillator leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal;

And canceling the local oscillator leakage cancellation signal module, configured to cancel the local oscillator leakage signal in the up-converted signal or the down-converted signal by using the local oscillator leakage cancellation signal, and eliminate the local oscillator in the up-converted signal or the down-converted signal Leakage signal.

In an embodiment of the present disclosure, the acquiring a local oscillator leakage cancellation signal module includes:

a coupler for performing a local oscillator leakage signal extraction process by using an up-converted signal or a down-converted signal output from the mixer to obtain a local oscillator leakage signal;

An amplitude detecting and adjusting unit, configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal, to obtain a local oscillator leakage amplitude canceling signal equal to the amplitude of the local oscillator leakage signal;

The phase detecting and adjusting unit is configured to perform phase adjustment on the local oscillator leakage amplitude canceling signal according to the phase of the local oscillator leakage signal, to obtain a local oscillator leakage canceling signal having the same amplitude and opposite phase as the local oscillator leakage signal.

In an embodiment of the present disclosure, the canceling the local oscillator leakage cancellation signal module includes:

The combiner is configured to cancel the local oscillator leakage signal in the up-converted signal or the down-converted signal by using the local oscillator leakage cancellation signal, and eliminate the local oscillation leakage signal in the up-converted signal or the down-converted signal.

Obtaining an up-converted signal or a down-converted signal including a local oscillator leakage signal;

Obtaining an amplitude and a phase of the local oscillation leakage signal from the up-converted signal or the down-converted signal, and performing amplitude and phase adjustment on the local oscillation signal according to the amplitude and phase of the local oscillation leakage signal, thereby obtaining leakage with the local oscillator a local oscillator leakage cancellation signal having equal signal amplitudes and opposite phases;

Using the local oscillator leakage cancellation signal to cancel the local oscillator leakage signal in the up-converted signal or the down-converted signal, and cancel the local oscillator leakage signal in the up-converted signal or the down-converted signal number.

In an embodiment of the present disclosure, the obtaining the amplitude and phase of the local oscillation leakage signal from the up-converted signal or the down-converted signal includes:

Obtaining the amplitude and phase of the local oscillator leakage signal by amplitude and phase analysis;

In an embodiment of the present disclosure, the amplitude and phase of the local oscillation leakage signal, and the amplitude and phase adjustment of the local oscillation signal include:

In an embodiment of the present disclosure, the performing amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillation leakage signal includes:

The local oscillator signal voltage value and the local oscillator leakage signal voltage value are obtained by inputting the local oscillator signal into the detector for detection, and inputting the local oscillator leakage signal into the detector for detection;

And inputting the obtained local oscillation signal voltage value and the local oscillation leakage signal voltage value into the amplitude comparator to obtain an amplitude control voltage of the local oscillation signal and the local oscillation leakage signal;

Amplitude adjustment is performed on the local oscillator signal input to the controllable attenuator by using the amplitude control voltage to obtain a local oscillator signal of the same amplitude that is the same as the amplitude of the local oscillator leakage signal.

In an embodiment of the present disclosure, the phase adjusting the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal includes:

The phase control voltage of the local oscillation leakage signal and the same amplitude local oscillation signal is obtained by inputting the local oscillation leakage signal and the same amplitude local oscillation signal into the phase detector;

Using the phase control voltage to input the same amplitude local oscillator signal input to the control phase shifter The line phase adjustment obtains a local oscillator leakage cancellation signal that is opposite in phase to the local oscillator leakage signal.

Obtaining a voltage value of the local oscillation leakage signal according to the amplitude of the local oscillation leakage signal;

Using the obtained voltage value, the amplitude of the local oscillator signal input to the resistor attenuator is adjusted to obtain the same local oscillator signal as the local oscillator leakage signal.

The first RF is obtained by counting the length of the RF transmission line between the local oscillator signal path coupler and the mixer, and controlling the length of the RF transmission line between the mixer and the combiner signal path of the mixer output. Total length of the transmission line;

And controlling the resistance of the RF transmission line between the local oscillator signal path coupler and the resistor attenuator according to the obtained total length of the first RF transmission line, and controlling the resistance of the resistor attenuator to output the same amplitude local oscillator signal path resistor attenuator to The length of the radio frequency transmission line between the combiners is such that the total length of the second radio frequency transmission line that differs from the total length of the first radio frequency transmission line by one radio frequency phase is such that the phase of the same local oscillator signal and the local oscillator leakage signal are opposite.

According to the solution provided by the embodiment of the present disclosure, the cancellation of the local oscillator leakage is completed with less hardware cost, which saves the cost of research and development and commercial use; the circuit structure is simple, the PCB layout is difficult, the PCB area is saved, and the local oscillator leakage is realized. Elimination, no software algorithm coordination, better real-time performance; circuit adaptive, can use different circuit forms to complete the local oscillator leakage according to different application scenarios.

DRAWINGS

The drawings described herein are provided to provide a further understanding of the present disclosure, which is a part of the present disclosure, and the description of the present disclosure and the description thereof are not intended to limit the disclosure. In the drawing:

1 is a schematic diagram of a device for eliminating local oscillator leakage according to an embodiment of the present disclosure;

2 is a flow chart of a method for eliminating local oscillator leakage according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of another apparatus for eliminating local oscillator leakage according to an embodiment of the present disclosure; FIG.

4 is a flow chart of another method for eliminating local oscillator leakage provided by an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of a local oscillator leakage cancellation device according to an embodiment of the present disclosure; FIG.

6 is a schematic diagram of a structure of a local oscillation leakage cancellation circuit according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of a structure 2 of a local oscillator leakage cancellation circuit according to an embodiment of the present disclosure.

detailed description

The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

1 is a schematic diagram of an apparatus for eliminating local oscillator leakage according to an embodiment of the present disclosure. As shown in FIG. 1, the apparatus for eliminating local oscillator leakage includes: a coupler 101 for up-converting signals outputted by a mixer or The down-converted signal is subjected to a local oscillator leakage signal extraction process to obtain a local oscillator leakage signal, and the amplitude detecting and adjusting module 102 is configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal to obtain a leakage signal with the local oscillator. a local oscillator leakage amplitude cancellation signal having an equal amplitude; the phase detection and adjustment module 103 is configured to perform phase adjustment on the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, to obtain an amplitude equal to the local oscillation leakage signal and a phase The opposite local oscillator leakage cancels the signal.

The amplitude detecting and adjusting module 102 includes: an amplitude detecting unit, configured to perform amplitude analysis on the local oscillator leakage signal to obtain an amplitude of a local oscillator leakage signal; and an amplitude adjusting unit configured to leak according to the local oscillator The amplitude of the signal adjusts the amplitude of the local oscillator signal to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal. The phase detecting and adjusting module 103 includes: a phase detecting unit configured to obtain a phase of the local oscillator leakage signal by performing phase analysis on the local oscillator leakage signal; and a phase adjusting unit configured to perform a leakage signal according to the local oscillator The phase adjusts the phase of the local oscillator leakage amplitude canceling signal to obtain a local oscillator leakage canceling signal having the same amplitude and opposite phase as the local oscillator leakage signal.

2 is a flow chart of a method for eliminating local oscillator leakage according to an embodiment of the present disclosure, as shown in FIG. 2 . As shown, the method of eliminating local oscillator leakage includes:

Step S201: performing local oscillator leakage signal extraction processing on the up-converted signal or the down-converted signal output from the mixer to obtain a local oscillation leakage signal;

Step S202: performing amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillation leakage signal, and obtaining a local oscillation leakage amplitude cancellation signal equal to the amplitude of the local oscillation leakage signal;

Step S203: Perform phase adjustment on the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtain a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.

The amplitude adjustment of the local oscillation signal according to the amplitude of the local oscillation leakage signal, and obtaining the local oscillation leakage amplitude cancellation signal equal to the amplitude of the local oscillation leakage signal includes: performing amplitude analysis on the local oscillation leakage signal, Obtaining the amplitude of the local oscillator leakage signal; performing amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal to obtain a local oscillator leakage amplitude cancellation signal equal to the local oscillator leakage signal amplitude.

The phase adjustment of the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtaining a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal includes: leaking the local oscillator The signal is phase-analyzed to obtain the phase of the local oscillator leakage signal; the phase of the local oscillator leakage amplitude canceling signal is phase-adjusted according to the phase of the local oscillator leakage signal, and the local oscillator leakage offset with the amplitude of the local oscillator leakage signal and the opposite phase is obtained. signal.

FIG. 3 is a schematic diagram of another apparatus for eliminating local oscillator leakage according to an embodiment of the present disclosure. As shown in FIG. 3, the apparatus for eliminating local oscillator leakage includes: a signal output module 301 for outputting a signal including a local oscillator leakage signal. a variable frequency signal or a down-converted signal; a local oscillator leakage cancellation signal module 302, configured to obtain an amplitude and a phase of the local oscillator leakage signal from the up-converted signal or the down-converted signal, and according to the amplitude of the local oscillator leakage signal Phase-adjusting the amplitude and phase of the local oscillator signal to obtain a local oscillator leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal; and canceling the local oscillation leakage cancellation signal module 303 for utilizing the local oscillation leakage cancellation signal pair The local oscillator leakage signal in the up-converted signal or the down-converted signal is subjected to cancellation processing to eliminate the local oscillation leakage signal in the up-converted signal or the down-converted signal.

The acquiring the local oscillator leakage cancellation signal module 302 includes: a coupler configured to perform a local oscillator leakage signal extraction process by using an up-converted signal or a down-converted signal output from the mixer to obtain a local oscillator leakage signal; amplitude detection and a regulator, configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal, to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillation leakage signal; and a phase detection and regulator for The phase of the local oscillation leakage signal adjusts the phase of the local oscillation leakage amplitude cancellation signal to obtain a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.

The canceling the local oscillator leakage canceling signal module 303 includes: a combiner for canceling the local oscillator leakage signal in the up-converted signal or the down-converted signal by using the local oscillator leakage canceling signal, and eliminating the The local oscillator leakage signal in the variable frequency signal or the down converted signal.

The acquiring local oscillator leakage cancellation signal module 302 includes: a detecting unit, configured to perform detection by inputting a local oscillator signal into the detector, and input the local oscillator leakage signal into the detector for detection, to obtain a local oscillator signal. a voltage value and a local oscillator leakage signal voltage value; obtaining an amplitude control voltage unit for inputting the obtained local oscillator signal voltage value and the local oscillation leakage signal voltage value into the amplitude comparator to obtain the local oscillator signal and the The amplitude control voltage of the local oscillation leakage signal; the first amplitude adjustment unit is configured to perform amplitude adjustment on the local oscillation signal input to the controllable attenuator by using the amplitude control voltage, to obtain a magnitude of the leakage signal with the local oscillation Same same amplitude local oscillator signal. And obtaining a phase control voltage module, configured to obtain a phase control voltage of the local oscillation leakage signal and the same amplitude local oscillation signal by inputting the local oscillation leakage signal and the same amplitude local oscillation signal into the phase detector; The first phase adjustment unit is configured to perform phase adjustment on the same-amplitude local oscillation signal input to the control phase shifter by using the phase control voltage to obtain a local oscillation leakage cancellation signal having a phase opposite to the local oscillation leakage signal.

The acquiring the local oscillator leakage cancellation signal module 302 includes: acquiring a voltage value unit, configured to obtain a voltage value of the local oscillation leakage signal according to the amplitude of the local oscillation leakage signal; and a second amplitude adjustment unit, configured to: Using the obtained voltage value, the amplitude of the local oscillator signal input to the resistor attenuator is adjusted to obtain the same local oscillator signal as the local oscillator leakage signal. And a statistical unit for counting the length of the RF transmission line between the local oscillator signal path coupler and the mixer and controlling the local oscillator leakage signal path of the mixer output between the mixer and the combiner The length of the RF transmission line is obtained to obtain the total length of the first RF transmission line; and the second phase adjustment unit is configured to control the RF between the local oscillator signal path coupler and the resistance attenuator according to the total length of the obtained first RF transmission line The length of the transmission line and the length of the RF transmission line between the resistor local attenuator and the resistor attenuator output resistor attenuator to the combiner, and obtaining a second RF transmission line that differs from the total length of the first RF transmission line by one RF phase The total length is such that the same local oscillator signal is opposite in phase to the local oscillator leakage signal.

4 is a flow chart of another method for eliminating local oscillator leakage according to an embodiment of the present disclosure. As shown in FIG. 4, the method for eliminating local oscillator leakage includes:

Step S401: Acquire an up-conversion signal or a down-conversion signal including a local oscillation leakage signal;

Step S402: Obtain an amplitude and a phase of the local oscillation leakage signal from the up-converted signal or the down-converted signal, and perform amplitude and phase adjustment on the local oscillation signal according to the amplitude and phase of the local oscillation leakage signal, and obtain the The local oscillator leakage signal has the same amplitude and opposite phase of the local oscillator leakage cancellation signal;

Step S403: cancel the local oscillator leakage signal in the up-converted signal or the down-converted signal by using the local oscillator leakage cancellation signal to eliminate the local oscillation leakage signal in the up-converted signal or the down-converted signal.

The amplitude and phase of the local oscillator leakage signal obtained from the up-converted signal or the down-converted signal include: performing local oscillator leakage signal extraction processing on the up-converted signal or the down-converted signal output from the mixer, thereby obtaining the present a vibration leakage signal; obtaining amplitude and phase of the local oscillation leakage signal by performing amplitude and phase analysis on the local oscillation leakage signal;

The amplitude and phase adjustment of the local oscillator signal according to the amplitude and phase of the local oscillator leakage signal includes: performing amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal, and obtaining an amplitude equal to the local oscillator leakage signal. The local oscillation leakage amplitude canceling signal; phase-adjusting the local oscillation leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtaining a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.

The amplitude adjustment of the local oscillator signal according to the amplitude of the local oscillator leakage signal includes: detecting by inputting a local oscillator signal into the detector, and inputting the local oscillator leakage signal The detection is performed in the detector to obtain the local oscillator signal voltage value and the local oscillator leakage signal voltage value; and the obtained local oscillator signal voltage value and the local oscillator leakage signal voltage value are input into the amplitude comparator to obtain the local oscillator. And an amplitude control voltage of the signal and the local oscillation leakage signal; using the amplitude control voltage to perform amplitude adjustment on a local oscillation signal input to the controllable attenuator, to obtain a same amplitude range as the amplitude of the local oscillation leakage signal Vibration signal.

The amplitude adjustment of the local oscillation signal according to the amplitude of the local oscillation leakage signal includes: obtaining a voltage value of the local oscillation leakage signal according to the amplitude of the local oscillation leakage signal; and using the obtained voltage value, The local oscillator signal input to the resistor attenuator is amplitude-adjusted to obtain the same local oscillator signal as the local oscillator leakage signal.

The phase adjustment of the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal includes: obtaining the local oscillator by inputting a local oscillation leakage signal and the same amplitude local oscillation signal into a phase detector a phase control voltage of the leakage signal and the same amplitude local oscillator signal; phase adjustment of the same amplitude local oscillator signal input to the control phase shifter by using the phase control voltage to obtain a phase opposite to the local oscillation leakage signal The local oscillator leaks the cancellation signal.

The phase adjustment of the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal includes: counting the length of the radio frequency transmission line between the local oscillator signal path coupler and the mixer, and controlling the mixer output. The local oscillator leakage signal path is the length of the RF transmission line between the mixer and the combiner, and the total length of the first RF transmission line is obtained; according to the total length of the obtained first RF transmission line, by controlling the local oscillator signal path coupler to The length of the RF transmission line between the resistor attenuators and the length of the RF transmission line between the same amplitude local oscillator signal path resistance attenuator and the combiner of the control resistor attenuator are different from the total length of the first RF transmission line The total length of the second RF transmission line of the RF phase is such that the same local oscillator signal is opposite in phase to the local oscillator leakage signal.

FIG. 5 is a schematic diagram of a local oscillator leakage canceling device according to an embodiment of the present disclosure. As shown in FIG. 5, the local oscillator leakage canceling device includes the following components:

1. Mixer: A circuit whose output signal frequency is equal to the sum of the frequencies of the two input signals, the difference, or other combination of the two.

2. Coupler: In the RF system, it is often necessary to divide the microwave power into several paths proportionally. The component that realizes this function is called the power distribution component, that is, the coupler.

3. Phase detector: It is a device that can identify the phase difference of the input signal, and is a circuit that determines the phase difference between the output voltage and the two input signals.

4. Phase shifter: A device capable of adjusting the phase of a wave

5. Detector: A device that can convert power into voltage

6. Combiner: A device that can combine or divide signals. The combiner has two branch ends and one composite port.

The intermediate frequency or RF signal (IF/RF) and the local oscillator signal are respectively connected to the two input ports of the mixer; a coupler 1 and a coupler 2 are added to the input end of the local oscillator signal and the output of the mixer respectively, and the local oscillator signal A part of the local oscillator signal is coupled through the coupler 1, and the frequency of the local oscillator signal generated by the coupling remains unchanged. After the amplitude detection, the adjustment module and the phase detection and the adjustment module respectively, the local oscillator coupling signal and the local oscillator signal pass through the mixer. The generated local oscillator leakage signals have the same amplitude and phase difference of 180°, and the two signals cancel each other out, thereby completing the purpose of eliminating the local oscillator leakage.

FIG. 6 is a schematic diagram of a structure of a local oscillator leakage cancellation circuit according to an embodiment of the present disclosure. Figure 6 shows the amplitude detection and adjustment module, phase detection and adjustment module in a specific circuit. The amplitude detection and adjustment module is composed of a detector 1, an amplitude comparator, a detector 2, and a controllable attenuator, and realizes the process of amplitude adjustment: the detector 1 and the detector 2 respectively detect the local oscillation signal generated by the coupling of the coupler 1 and The coupler 2 couples the power magnitude of the local oscillator leakage signal generated by the local oscillator leakage signal and converts it into a voltage value. The two voltage values generate a control voltage through the amplitude comparator to control the attenuation of the attenuator, so that the coupled signal Has the same magnitude as the leak signal. The phase detection and adjustment module is composed of a phase detector and a phase shifter to realize the phase adjustment process: a part of the local oscillator leakage signal is coupled through the coupler 2, and the local oscillator signal passing through the attenuator is sent to the phase detector, the phase detector The phase difference of the two signals is outputted by the voltage, and the generated voltage is used to control the phase shifter, so that the phase of the local oscillator signal output by the phase shifter has a phase difference with the phase of the local oscillator leakage signal output by the coupler 2. This is because the phase of the RF signal changes as the length of the RF trace changes. The length of the RF trace between the coupler 2 and the combiner, and the length of the RF trace between the phase shifter and the combiner will be changed due to different circuit application scenarios. In this case, only the phase detector needs to be changed. The loop between the phase shifter and the phase shifter ensures that the coupled local oscillator signal and the local oscillator leakage signal are 180° out of phase, so that the two signals are in the same amplitude and in opposite phase, and cancel each other after passing through the combiner.

That is to say, firstly, the intermediate frequency/radio frequency signal and the local oscillator signal are respectively sent into the mixer, and the output signal is measured by the spectrum analyzer, and the output signal includes the local oscillator leakage signal, and the local oscillator leakage signal can be obtained from the spectrum. Size; then add a known coupling degree of the coupler 1 to the local oscillator signal path to ensure that the local oscillator signal power generated by the coupler 1 coupling is greater than the local oscillator leakage signal power. In this way, in the subsequent debugging process, due to the inconsistency of the mixer batches, the power of the local oscillator leakage signal is inconsistent, and the amplitude of the local oscillator signal generated by the coupling and the local oscillator leakage signal can be adjusted by adjusting the attenuation amount of the attenuator. The amplitudes remain equal.

Then, the coupling degree of the coupler 1 and the coupler 2 is known, the relationship between the attenuation amount of the attenuator and its bias voltage is known (pre-measured or given by its specification), and the comparison output voltage value of the amplitude comparator The size can be adjusted by its peripheral circuitry. The signal generated by the coupler 1 coupled with the local oscillator signal passes through the detector 1 and then outputs the detection voltage V1. The signal generated by the coupler 2 coupled with the local oscillation leakage signal passes through the detector 2 and then outputs the detection voltage V2, and V1 and V2 are generated after passing through the amplitude comparator. A voltage value is used to control the attenuation of the attenuator. The amplitude comparator peripheral circuit can be adjusted to make the local oscillator signal coupled by the coupler 1 equal to the local oscillator leakage signal power value after passing through the mixer.

Finally, the signal generated by the coupler 1 coupled with the local oscillator signal and the signal generated by the coupler 2 coupled with the local oscillator leakage signal are simultaneously input to the two input ports of the phase detector, and the phase detector distinguishes the phase difference between the two signals, and The phase difference is converted into a voltage value to control the phase shifter to phase shift the signal generated by the coupler 1 coupled local oscillator signal, and the phase change amount can be controlled by changing the loop between the phase detector and the phase shifter. In different application scenarios, the lengths of L1 and L2 are different in FIG. 6. According to the radio frequency transmission line theory, the phase of the radio frequency signal changes with the length of the radio frequency line, so the corresponding ring needs to be changed in the corresponding application scenario. The way the two signals arrive at the ends of the combiner are opposite in phase. Through the above method, the two input ports of the combiner can be ensured, and the local oscillator signal coupled through the coupler and the local oscillator signal leaked by the local oscillator through the mixer are in the same amplitude and reversed phase. Achieve the elimination of local oscillator leakage.

A typical circuit for canceling the leakage of the local oscillator will be described below with reference to FIG. 6:

(1) obtaining the corresponding relationship between the attenuation amount of the attenuator and the bias voltage, that is, the bias voltage changes by ΔV, and the attenuation value of the corresponding attenuator changes by ΔP;

(2) Adjust the comparison output value of the amplitude comparator to ensure that the voltage V1 of the detection output of the detector 1 and the voltage V2 of the detection output of the detector 2, V1 and V2 pass through the amplitude comparator, and the comparison output voltage generated by the comparator controls the attenuation. The amount of attenuation of the device is such that the local oscillator signal coupled by the coupler is equal to the power of the local oscillator leakage signal after passing through the mixer;

(3) The local oscillator leakage signal coupled by the coupler 2 and the local oscillator signal coupled to the coupler 1 are sent to the phase detector, and the phase detector converts the phase difference between them into a voltage value to control the phase shifter pair. The local oscillator signal coupled by the coupler 1 is phase-shifted so that the two signals are inverted before entering the combiner;

(4) The coupled local oscillator signal and the local oscillator leakage signal are at the same amplitude and opposite phase at the input end of the combiner. After the two signals enter the combiner, they cancel each other out, and the purpose of eliminating the local oscillator leakage is achieved.

7 is a schematic diagram of a second structure of a local oscillation leakage cancellation circuit according to an embodiment of the present disclosure. As shown in FIG. 7, the coupler 2, the amplitude detection and adjustment module, the phase detection and adjustment module in the dotted line frame of FIG. 5 are removed, and the adjustable The attenuator is changed to a resistor attenuator. The amplitude adjustment is achieved by controlling the resistance attenuator, and the phase adjustment is achieved by controlling the length of the RF transmission line. The specific implementation manner is: controlling the length of the RF transmission line (L1+L2) between the coupler and the combiner through the mixer, and the length of the RF transmission line (L3+L4) between the coupler and the combiner through the resistor attenuator. The local oscillator signal and the local oscillator signal coupled by the coupler have a phase difference of 180°; the local oscillator signal coupled by the coupler can be controlled by the resistor attenuator to have the same amplitude as the local oscillator leakage signal, and the two signal phases are Eliminate, so the output port only has RF/IF (RF/IF) signals. This circuit structure is suitable for narrow-band signals, and once it is made into a product, it cannot be debugged. The advantage is that the circuit is simpler, the circuit stability is high, and the cost is low, which is suitable for special scenes.

That is to say, the coupler 2, the amplitude detection and adjustment module and the phase detection and adjustment module in the device of Fig. 5 are removed, and the adjustable attenuator is changed to a resistance attenuator. The attenuation value of the resistor attenuator can be determined by testing the local oscillator leakage magnitude in the output spectrum using a spectrum analyzer; The relationship between the phase velocity, the frequency and the dielectric constant in the RF transmission line can be obtained by using the RF transmission line theory, and the phase angle change amount θ corresponding to the RF transmission line length change amount L can be obtained. By controlling the length of the RF transmission line, the two signals entering the combiner are 180° out of phase. The phase determination also needs to take into account the phase change caused by the mixer. In the actual debugging process, the output of the combiner is connected to the spectrum analyzer, and the length of the RF transmission line is constantly changed to make the observation on the spectrum analyzer. The power value of the local leakage signal reaches the minimum value. The default is that the phase of the two signals arriving at the combiner is 180° out of phase. That is, the phase of (L1+L2+Mixer) is 180° out of phase with (L3+L4). Among them, in the amplitude detection and adjustment module, the phase detection and adjustment module, the method of simultaneous control by hardware and software is used to achieve the purpose of amplitude modulation and phase modulation to complete the elimination of the local oscillator leakage.

According to the solution provided by the embodiment of the present disclosure, two radio frequency signals are utilized, and if the amplitudes are equal and the phases are opposite, the principle that they combine to cancel each other. That is, before the local oscillator signal enters the mixer, a part of the local oscillator signal is coupled through the coupler, and the coupled local oscillator signal passes through the amplitude adjusting device and the phase adjusting device, and then enters one of the input ports of the combiner; the mixer output The RF signal with the local oscillator leakage signal enters the other input port of the combiner through the RF transmission line; the coupled local oscillator signal and the local oscillator leakage signal have the same amplitude, and the phases are 180° out of phase, and cancel each other after the combiner to reach The purpose of eliminating the leakage of the local oscillator.

Although the present disclosure has been described in detail above, the present disclosure is not limited thereto, and various modifications may be made by those skilled in the art in accordance with the principles of the present disclosure. Therefore, modifications made in accordance with the principles of the present disclosure are to be understood as falling within the scope of the present disclosure.

Industrial applicability

Claims

A device for eliminating local oscillator leakage, including:

a coupler for performing a local oscillator leakage signal extraction process on the upconverted signal or the downconverted signal output from the mixer to obtain a local oscillator leakage signal;

An amplitude detecting and adjusting module, configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal, to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal;

The phase detection and adjustment module is configured to perform phase adjustment on the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, to obtain a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.
The apparatus of claim 1 wherein said amplitude detection and adjustment module comprises:

An amplitude detecting unit configured to perform amplitude analysis on the local oscillator leakage signal to obtain an amplitude of the local oscillator leakage signal;

And an amplitude adjustment unit configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillation leakage signal to obtain a local oscillation leakage amplitude cancellation signal equal to the amplitude of the local oscillation leakage signal.
The apparatus of claim 1 wherein said phase detection and adjustment module comprises:

a phase detecting unit, configured to perform phase analysis on the local oscillator leakage signal to obtain a phase of the local oscillator leakage signal;

The phase adjustment unit is configured to perform phase adjustment on the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, to obtain a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.
A method of eliminating local oscillator leakage, including:

The local oscillator leakage signal is obtained by performing a local oscillator leakage signal extraction process on the up-converted signal or the down-converted signal output from the mixer;

Performing amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal;

Phase-adjusting the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtaining a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.
The method according to claim 4, wherein the amplitude adjustment of the local oscillation signal according to the amplitude of the local oscillation leakage signal to obtain a local oscillation leakage amplitude cancellation signal equal to the amplitude of the local oscillation leakage signal comprises:

Performing amplitude analysis on the local oscillator leakage signal to obtain the amplitude of the local oscillator leakage signal;

The amplitude of the local oscillator signal is adjusted according to the amplitude of the local oscillator leakage signal to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal.
The method according to claim 4, wherein the phase adjustment of the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal is performed, and the local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal is obtained. :

Phase analysis of the local oscillator leakage signal to obtain a phase of the local oscillator leakage signal;

Phase-adjusting the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtaining a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.
A device for eliminating local oscillator leakage, including:

a signal output module, configured to output an up-converted signal or a down-converted signal including a local oscillator leakage signal;

Obtaining a local oscillation leakage cancellation signal module, configured to obtain an amplitude and a phase of a local oscillation leakage signal from the up-converted signal or the down-converted signal, and perform amplitude and phase on the local oscillation signal according to the amplitude and phase of the local oscillation leakage signal Adjusting to obtain a local oscillator leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal;

And canceling the local oscillator leakage cancellation signal module, configured to cancel the local oscillator leakage signal in the up-converted signal or the down-converted signal by using the local oscillator leakage cancellation signal, and eliminate the local oscillator in the up-converted signal or the down-converted signal Leakage signal.
The apparatus according to claim 7, wherein the acquiring the local oscillator leakage cancellation signal module comprises:

a coupler for performing a local oscillator leakage signal extraction process by using an up-converted signal or a down-converted signal output from the mixer to obtain a local oscillator leakage signal;

An amplitude detecting and adjusting unit, configured to perform amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal, to obtain a local oscillator leakage amplitude canceling signal equal to the amplitude of the local oscillator leakage signal;

The phase detecting and adjusting unit is configured to perform phase adjustment on the local oscillator leakage amplitude canceling signal according to the phase of the local oscillator leakage signal, to obtain a local oscillator leakage canceling signal having the same amplitude and opposite phase as the local oscillator leakage signal.
The apparatus according to claim 7, wherein the canceling the local oscillator leakage cancellation signal module comprises:

The combiner is configured to cancel the local oscillator leakage signal in the up-converted signal or the down-converted signal by using the local oscillator leakage cancellation signal, and eliminate the local oscillation leakage signal in the up-converted signal or the down-converted signal.
A method of eliminating local oscillator leakage, including:

Obtaining an up-converted signal or a down-converted signal including a local oscillator leakage signal;

Obtaining an amplitude and a phase of the local oscillation leakage signal from the up-converted signal or the down-converted signal, and performing amplitude and phase adjustment on the local oscillation signal according to the amplitude and phase of the local oscillation leakage signal, thereby obtaining leakage with the local oscillator a local oscillator leakage cancellation signal having equal signal amplitudes and opposite phases;

The local oscillation leakage signal in the up-converted signal or the down-converted signal is cancelled by the local oscillation leakage cancellation signal, and the local oscillation leakage signal in the up-converted signal or the down-converted signal is eliminated.
The method according to claim 10, wherein said obtaining a magnitude and a phase of the local oscillation leakage signal from said up-converted signal or a down-converted signal comprises:

The local oscillator leakage signal is obtained by performing a local oscillator leakage signal extraction process on the up-converted signal or the down-converted signal output from the mixer;

Obtaining the amplitude and phase of the local oscillator leakage signal by amplitude and phase analysis;
The method according to claim 10, wherein the amplitude and phase of the local oscillation leakage signal, and the amplitude and phase adjustment of the local oscillation signal comprise:

Performing amplitude adjustment on the local oscillator signal according to the amplitude of the local oscillator leakage signal to obtain a local oscillator leakage amplitude cancellation signal equal to the amplitude of the local oscillator leakage signal;

Phase-adjusting the local oscillator leakage amplitude cancellation signal according to the phase of the local oscillation leakage signal, and obtaining a local oscillation leakage cancellation signal having the same amplitude and opposite phase as the local oscillation leakage signal.