KR20090120820A - Auto gain control system - Google Patents

Abstract

PURPOSE: An auto gain control system is provided to maintain an output signal of a power amplifier module stably by calculating the amount of gain change accurately. CONSTITUTION: In an auto gain control system, a first attenuator(110) is connected to a transmission output terminal of a transceiver(200). A second attenuator(120) is connected to an input terminal of a power amplifier module(300), and the first attenuator is operated by a digital method. A second attenuator is operated by an analog method, and a combiner(130) is connected between an output terminal and an RF switch(400) of the power amplifier module. A sensor(140) produces a sensing signal by sensing the output change of the power amplifier module. A filter(150) delays a signal, and a comparator(160) compares the sensed signal with a reference voltage recorded at a storage(170) by 0.01V unit.

Description

AC System {Auto Gain Control system}

Embodiments relate to an AGC system.

1 is a block diagram schematically illustrating the components of the communication module 10.

Referring to FIG. 1, the communication module 10 includes an antenna 11, an RF switch 12, a receiver 13, a transceiver 14, an attenuator 15, and a power amplifier module (PAM) 16. ), A combiner 17, a detector 18, a comparator 19 and a storage 20.

Among them, the attenuator 15, the combiner 17, the detector 18, the comparator 19, and the storage 20 constitute an AGC (Auto Gain Control) system (A).

The amplification gain of the power amplification module 16 may vary according to an external environment, and the output signal of the power amplification module 16 changes according to the gain change.

In this case, the combiner 17 couples the output signal of the power amplification module 16 to the detector 18, and the detector 18 senses the power of the coupled output signal to detect the comparator signal. To 19.

The comparator 19 compares the detected signal with a reference voltage signal transmitted from the storage unit 20 and transmits a comparison result signal to the attenuator 15.

Accordingly, the attenuator 15 attenuates the power of the input signal of the power amplification module 16 according to the comparison result signal or amplifies a previously attenuated signal again so that the output of the power amplification module 16 is constant. Keep it.

That is, the gain of the entire transmission path may be kept constant by attenuating or amplifying the signal input to the power amplification module 16 inversely by the amount of change in the gain of the power amplification module 16.

In general, the attenuator 15 and the comparator 19 are configured together with the transceiver 14 in a single chip, in which case the attenuator 15 is designed to operate digitally rather than analogically.

Accordingly, the attenuator 15 adjusts the gain in a constant level unit, for example, 1 dB unit, and the "gain vibration phenomenon" is generated by this digital attenuation.

This will be described in more detail with reference to FIGS. 2 and 3.

2 is a data table measuring changes in power and gain of an input / output signal of the power amplifier module 16 according to the operation of the attenuator 15, and FIG. 3 shows the power amplifier according to the operation of the attenuator 15. It is a graph showing the power change of the output signal of the module 16.

First, in the initial state, the power of the RF signal is attenuated by -5 dBm by the attenuator 15, so that the output signal of the power amplification module 16, whose gain is designed to be 30 dBm, is 25 dBm. At this time, the detector 18 detects the voltage of the output signal as 1.20V, which is the same as the reference voltage of 1.20V of the storage unit 20, so that the output signal can be maintained at 25dBm.

Second, in the first state, when the gain and the output signal of the power amplifier module 16 increases by 0.3dB as the external environment changes, the detector 18 detects the voltage of the output signal as 1.21V.

Third, in the second state, the comparator 19 compares the sensing signal 1.21V with the reference voltage of 1.20V and the attenuator 15 changes the attenuation value by 1dB from 5dB to 6dB as the comparison result signal becomes 0.1V. Let's do it.

Accordingly, the output signal of the power amplification module 16 becomes 24.3 dBm attenuated by 1 dB, and the detector 18 detects the voltage of the output signal as 1.17 V.

Fourth, in the third state, the comparator 19 compares the sensing signal 1.17V with the reference voltage of 1.20V and the attenuation value is reduced from 6dB to 5dB as the comparison result signal becomes -0.3V. Change by 1 dB.

Accordingly, the output signal of the power amplification module 16 becomes 25.3 dBm amplified by 1 dB, and the detector 18 again senses the voltage of the output signal as 1.21 V.

Fifth, in the fourth state, as the voltage of the output signal of the power amplification module 16 is detected as 1.21V, the operation of the second state is repeated, and the output signal of the power amplification module 16 is 24.3 dBm. Is adjusted.

Hereinafter, by repeating the second to fourth states, as shown in FIG. 3, the output signal of the power amplification module 16 exhibits a "gain vibration phenomenon" that rises and falls between 24.3 dBm and 25.3 dBm.

This is because the attenuator 15 does not correspond to the gain change 0.3 dB (first state) first generated in the power amplification module 16 in an analog manner, but adjusts the gain in units of 1 dB.

Therefore, the gain change of the power amplification module 16 is not canceled, and the deviation of the gain control is repeated according to the circulation structure of the AGC system, which causes a weakening of the transmission function of the communication module.

The embodiment provides an AGC system capable of optimizing the transmission function of a communication module by preventing a gain vibration phenomenon by compensating for a disadvantage of a digitally operated attenuator.

The AGC system according to the embodiment includes a first attenuator for digitally attenuating the RF signal of the transceiver; A second attenuator for attenuating the output signal of the first attenuator in an analog manner and transferring the attenuated signal to a power amplifier module; A coupler for coupling the output signal of the power amplifier module; A detector for sensing a power level of the signal coupled by the combiner and transferring the detected signal to a control signal of the second attenuator; And a comparator comparing the sensed signal with the reference voltage and transferring the comparison signal as a control signal of the first attenuator.

According to the embodiment, a gain oscillation phenomenon can be prevented from occurring in the AGC system due to the digitally operated attenuator.

In addition, when the AGC system is designed by mixing the digital attenuator and the analog attenuator, accurate gain control can be realized by accurately calculating the gain variation, and the output signal of the power amplifier module can be stably maintained.

Therefore, according to the embodiment, there is an effect that can improve the transmission and reception quality of the communication module.

With reference to the accompanying drawings, it will be described in detail for the AGC system according to the embodiment.

Hereinafter, in describing the embodiments, detailed descriptions of related well-known functions or configurations are deemed to unnecessarily obscure the subject matter of the present invention, and thus only the essential components directly related to the technical spirit of the present invention will be referred to. .

4 is a block diagram schematically illustrating the components of the AGC system 100 according to the embodiment, and FIG. 5 is an input / output signal of the power amplification module 300 according to the operation of the AGC system 100 according to the embodiment. A data table that measures the value at which the gain changes.

Referring to FIG. 4, the AGC system 100 according to the embodiment includes a first attenuator 110, a second attenuator 120, a combiner 130, a detector 140, a filter unit 150, and a comparator 160. It is configured to include a storage unit 170.

The first attenuator 110 is connected to the transmission output terminal of the transceiver 200, the second attenuator 120 is connected to the input terminal of the power amplifier module (PAM) (300).

In addition, the combiner 130 is connected between the output terminal of the power amplifier module 300 and the RF switch 400, and couples the output signal of the power amplifier module 300 to the detector 140.

According to an embodiment, the first attenuator 110 is an attenuator operated in a digital manner, and the second attenuator 120 is an attenuator operated in an analog manner.

For example, the first attenuator 110 may be configured as a single package chip together with the transceiver 200. The first attenuator 110 may have a predetermined unit change width according to a gain change width (or a change width of the output power) of the power amplification module 300. The attenuation value can be adjusted.

For example, the first attenuator 110 may be provided as a switch type attenuator. The switch type attenuator 110 may convert the fixed attenuation circuit and the through circuit into a switch.

In this case, the comparator 160 may also be configured with the transceiver 200 and a single package chip.

In an embodiment, the amplitude of change in the attenuation value unit of the first attenuator 110 is 1 dB.

The second attenuator 120 is a component for preventing a gain vibration phenomenon by supplementing the operation of the first attenuator 110, and thus setting the amount of change in attenuation of the second attenuator 120 changed to an analog state. The method is important.

For example, the second attenuator 120 may be provided as a semiconductor attenuator. The semiconductor attenuator 120 may be controlled by adjusting a bias voltage of a semiconductor device such as a transistor to continuously control the attenuation amount analogously.

Accordingly, the second attenuator 120 may receive the detection signal from the detector 140 as a control voltage and adjust the attenuation value linearly in proportion to the control voltage.

The gain variation may be improved by optimizing the unit change width of the attenuation value of the second attenuator 120 to the unit change width of the attenuation value of the first attenuator 110.

Hereinafter, an operation of the AGC system 100 according to an embodiment will be described with reference to FIG. 5. For convenience of description, an initial attenuation value of the first attenuator 110 is 3.0 dB, and the second attenuator ( The initial attenuation value of 120) is assumed to be 2.0 dB.

In addition, the standard gain of the power amplification module 300 is 30dB, the gain of the power amplification module 300 is changed linearly according to the change of the external environment.

In this case, the detector 140 detects a change in output of the power amplification module 300 and generates a linear detection signal.

Accordingly, the second attenuator 120 operated in an analog manner may receive a sensing signal as a control signal and linearly change the attenuation value.

However, the first attenuator 110 operated in a digital manner cannot receive a detection signal as a control signal as it is, and uses a comparison signal (digitized) compared at regular intervals through the comparator 160 as a control signal. .

In addition, the first attenuator 110 adjusts the attenuation value in units of 1 dB using the comparison signal as a control signal.

Therefore, as shown in FIG. 5, the unit sensing change width of the output power of the power amplification module 300 applicable to the comparator 160 is 0.3 dBm, and the unit change width of the sensing signal is 0.01 V units.

This is summarized as follows.

Output signal of power amplifier module 300 Detection signal of the detector 140 ... ... 25.3 dBm to 25.6 dBm 1.21 V 25.0 dBm to 25.3 dBm 1.20 V 24.7 dBm to 25.0 dBm 1.19 V 24.4 dBm to 24.7 dBm 1.18 V 24.1 dBm to 24.4 dBm 1.17 V ... ...

Therefore, the comparator 160 may compare the detection signal of the detector 140 with the reference voltage recorded in the storage unit 170 in 0.01V units.

Under this condition, a process of setting the unit change width of the attenuation value of the second attenuator 120 optimized for the first attenuator 110 will be described below.

In FIG. 5, the state is classified into the combiner 130, the detector 140, the filter unit 150, the comparator 160, the first attenuator 110, the second attenuator 120, and the power. The circulating state on the loop composed of the amplification module 300 is divided.

First, the initial state will be described.

The RF signal transmitted from the transceiver 200 to the first attenuator 110 is 0 dBm, and as described above, the initial attenuation value of the first attenuator 110 is 3.0 dB. In addition, the initial attenuation value of the second attenuator 120 is 2.0dB.

Therefore, the RF signal input to the power amplifier module 300 is -5dBm, the output signal of the power amplifier module 300 is 25.0dBm.

As shown in Table 1, since the output signal of the power amplification module 300 is 25.0dBm, the detector 140 that detects this generates a detection signal of 1.20V, and the comparator 160 detects the detection signal and the reference voltage. Since the same, the attenuation value of the first attenuator 110 is not adjusted.

Second, the first state will be described.

The first state is a case where a change occurs in the output signal of the power amplification module 300 according to a change in the external environment.

When the output of the power amplification module 300 increases linearly from 25.0 dBm to just before 25.3 dBm, the attenuation value of the first attenuator 110 is not adjusted for the reason described above, and the second attenuator 120 ), The attenuation value is changed linearly according to the detection signal of the detector 140.

At this time, if the linear change amount of the attenuation value of the second attenuator 120 is a variable "x", when the output power of the power amplifier module 300 reaches just before 25.3 dBm, the second attenuator 120 The attenuation value is (2.0 + x) dB.

That is, the variable "x" means the unit change width of the attenuation value of the second attenuator 120 when the output power of the power amplification module 300 changes by the unit detection change width comparable in the comparator 160.

Therefore, the power of the signal input to the power amplification module 300 is-(5-x) dBm, the gain of the power amplification module 300 is (30.3 + x) dB.

Subsequently, when the output of the power amplification module 300 becomes 25.3 dBm, the detection signal of the detector 140 reaches 1.21 V, and the comparator 160 compares the detection signal with a reference voltage.

Third, the second state will be described.

As a difference of 0.01V occurs between the detection signal and the reference voltage when the output of the power amplifier module 300 becomes 25.3dBm, the first attenuator 110 increases the attenuation value from 3dB to 4dB.

At this time, the attenuation value of the second attenuator 120 is maintained at (2.0 + x) dB, the gain of the power amplifier module 300 is maintained at (30.3 + x) dB.

Therefore, the power of the input signal of the power amplifier module 300 is (-6-x) dBm, the output of the power amplifier module 300 is 24.3 (= 30.3 + x-6-x) dBm.

Accordingly, the detector 140, as shown in Table 1, generates a sense signal of 1.17V.

Fourth, the third state will be described.

The detection signal of 1.17V generated by the detector 140 is transmitted to the second attenuator 120 and the filter unit 150.

For example, the filter unit 150 may be implemented as an RC filter including a resistor R and a capacitor C, and performs a function of delaying a signal.

Therefore, after the second attenuator 120 is operated, the comparator 160 may be operated.

Since the detection signal 1.17V has dropped 0.03V from the reference voltage 1.20V, the attenuation value of the second attenuator 120 is adjusted to (2.0-2x) dB.

Previously, when the reference voltage was increased by 0.01V, that is, when the output voltage was increased by 0.03 dBm, the unit change width of the attenuation value of the second attenuator 120 was defined as "x". Therefore, the second attenuator 120 in the second state was defined. 3x is subtracted from (2.0dB + xdB), which is the attenuation value of.), The attenuation value of the second attenuator 120 in the third state can be calculated as described above.

As the attenuation value of the second attenuator 120 is adjusted to (2.0-2x) dB, the output power of the power amplification module 300 becomes (24.3 + 3x) dBm.

At this time, the input power of the power amplifier module 300 is (-6 + 2x) dBm, the gain of the power amplifier module 300 maintains (30.3 + x) dB.

In addition, while the second attenuator 120 and the power amplifier module 300 are operated by the operation of the filter unit 150, the attenuation value of the first attenuator 110 is maintained in a second state, that is, 4 dB.

In this state, since the unit sensing change width of the output power of the power amplifier module 300 applicable to the comparator 160 is 0.3 dBm, the output power of the power amplifier module 300 in the third state (24.3 dBm + 3x). If the dBm) satisfies the range of "25.0 dBm (output power of the power amplifier module 300 in the initial state) ± 0.3 dBm", the first attenuator 110 maintains the gain value adjusted to 4 dB Can be.

That is, the gain vibration phenomenon of the first attenuator 110 can be prevented.

Such conditions are referred to as "gain vibration prevention conditions".

The cyclic operation of the AGC system 100 is formulated as follows.

"Output power of the power amplification module 300 in a third state (24.3 dBm + 3x dBm)" =

"Output power of the power amplifier module 300 in the initial state (25.0dBm)"

+ "Unit sense change width of the output power of the power amplifier module 300 comparable in the comparator 160 (0.3dBm, hereinafter referred to as" t ")"

"Unit change width of the attenuation value of the first attenuator 110 (1 dBm, hereinafter referred to as" k ")"

+ Three times the unit change width x of the attenuation value of the second attenuator 120 when the output power of the power amplification module 300 changes by the unit sense change width comparable in the comparator 160.

When Equation 1 is reflected in the gain vibration prevention condition and expressed using a variable whose units are canceled,

"25-t <25 + t-k + 3x <25 + t"

When the variables of Equation 2 are summarized,

"(k-2t) / 3 <x <k / 3".

Therefore, the unit change width, “x”, of the attenuation value of the second attenuator 120 optimized for the first attenuator 110 may be determined by Equation 3 below.

In the case of the embodiment, when calculating by applying the above assumed values, x was calculated to be greater than 0.1333dB and less than 0.3333dB, wherein the AGC system 100 according to the embodiment can be stably operated without gain vibration phenomenon. .

The present invention has been described above with reference to the preferred embodiments, which are merely examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications not illustrated above are possible. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a block diagram schematically showing the components of a communication module;

Figure 2 is a data table measuring the change in power and gain of the input and output signals of the power amplifier module according to the operation of the attenuator.

Figure 3 is a graph showing the power change of the output signal of the power amplifier according to the operation of the attenuator.

4 is a block diagram schematically illustrating components of an AGC system according to an embodiment.

5 is a data table measuring numerical values at which input / output signals and gains of a power amplification module change according to an operation of an AGC system according to an exemplary embodiment.

Claims (6)

A first attenuator for digitally attenuating the RF signal of the transceiver; A second attenuator for attenuating the output signal of the first attenuator in an analog manner and transferring the attenuated signal to a power amplifier module; A coupler for coupling the output signal of the power amplifier module; A detector for sensing a power level of the signal coupled by the combiner and transferring the detected signal to a control signal of the second attenuator; And And a comparator for comparing the sensed signal with a reference voltage and transferring a comparison signal as a control signal of the first attenuator. The method of claim 1, "Unit change width of the attenuation value of the second attenuator when the output power of the power amplifier module changes by the unit sense change width comparable in the comparator," x ", "Unit change width of attenuation value of said first attenuator" is referred to as "k", When "the unit sensing change width of the output power of the power amplifier module comparable in the comparator" is "t", AGC system that satisfies the formula "(k-2t) / 3 <x <k / 3". The method of claim 1, And a filter unit connected in parallel with the detector and the second attenuator and delaying the detection signal to the comparator. The method of claim 1, wherein the first attenuator AGC system consisting of the transceiver and a single package chip. The method of claim 1, wherein the comparator AGC system consisting of the transceiver and a single package chip. The method of claim 1, AGC system including a storage unit for transmitting the reference voltage to the comparator.

Images