CN100442656C

CN100442656C - Low-noise amplifier

Info

Publication number: CN100442656C
Application number: CNB2003101024575A
Authority: CN
Inventors: 林盈熙; 屈庆勋
Original assignee: Realtek Semiconductor Corp
Current assignee: Realtek Semiconductor Corp
Priority date: 2003-10-21
Filing date: 2003-10-21
Publication date: 2008-12-10
Anticipated expiration: 2023-10-21
Also published as: CN1610248A

Abstract

The present invention provides a low-noise amplifier which comprises a first transistor, a second transistor, an inductor and a resistor, wherein the inductor is connected between an RF output node and a working voltage. When a capacitor of the RF output node passes through the inductor, the harmonic frequency of the low-noise amplifier is 1.5 times larger than that of the working frequency by the capacitor. The capacitor can be a parasitic capacitor or a common capacitor of the RF output node. The low-noise amplifier is connected to independent ground passages, and the ground passages provide parasitic inductance through chip welding wires.

Description

The method of low noise amplifier and amplifying signal

Technical field

The invention provides a kind of amplifier, particularly a kind of low noise amplifier.

Background technology

Low noise amplifier has been used in the extensive fields, in radio frequency (RF) communication system as wireless network and mobile phone.Improve and promote the usefulness and the reliability of low noise amplifier and reduce the trend that its cost is current industry.

Fig. 1 is the schematic diagram of traditional low noise amplifier 10, with a dotted line (on-chip) and chip in the chip outer (off-chip) is made a distinction among Fig. 1.Low noise amplifier 10 includes a transistor 22, and transistor 22 has drain electrode, is connected in an operating voltage Vdd via first inductor 26.One RF input signal (RF input signal) is connected to the grid of transistor 22 via second inductor 28, and the output signal of low noise amplifier 10 is via the drain electrode output of transistor 22.The grid of transistor 22 is connected to current mirror circuit 24, and current mirror circuit 24 provides bias current via resistor 25.The source electrode of transistor 22 is connected to ground connection 12 through the node Q in the chip, and chip interior nodes Q also makes current mirror circuit 24 ground connection.The work of low noise amplifier 10 is: the RF input signal via the input of RF input node can amplify according to the inductance of operating voltage Vdd, bias current and inductor 26,28,29.

When making low noise amplifier 10 according to the CMOS manufacturing process, except chip external ground 12, above-mentioned all elements all are arranged in the chip.Please refer to U.S. Patent number the 5th, 574, No. 405, it is the advantage of element in similar low noise amplifier shown in Figure 1 in the complete description chip.Yet the connection at node Q can cause relatively poor insulation effect and stability, and responsive to noise.Other shortcomings also comprise the frequency bandwidth with relative narrower and inductor 28 must be set and the increase chip area.

At U.S. Patent number the 6th, 198, another low noise amplifier has been described in No. 352, comprise a resistance, replace the inductor 28 in the low noise amplifier 10.Its shortcoming is that this resistance can cause corresponding power loss under DC mode, the instability of the drain voltage of transistor 22, and the increase of noise.

Summary of the invention

Main purpose of the present invention is to provide the low noise amplifier of a kind of structure-improved and preferable manufacture method.

Low noise amplifier of the present invention includes first and second transistor, inductor and resistor.The grid of this first transistor be connected to an input node (RF input node), and its source electrode is connected to the first ground connection node.The source electrode of this transistor seconds be connected to the drain electrode of this first transistor, and the drain electrode of transistor seconds is connected to an output node (RF output node), and the grid of this transistor seconds is connected to first biasing simultaneously.Low noise amplifier of the present invention also includes a current mirror circuit, is connected to the grid of the first transistor, is used to provide a predetermined bias current.Inductor is connected between this output node and the operating voltage.Resistor is parallel to this inductor.

This output node has capacitance.This inductor and this capacitance decision resonance frequency, and bigger more than 1.5 times than an operating frequency (operating frequency) of being scheduled to, wherein this electric capacity can be the parasitic capacitance of this RF output node or is general electric capacity.By this this resonance frequency of inductor may command.

One transistorized source electrode of this current mirror, this first ground connection node and this capacitor are respectively via grounded circuit independently and ground connection.In addition, this first and second transistor, this inductor and this resistor are produced on the substrate by a CMOS manufacturing process, and the stray inductance of these a plurality of independent grounding paths is provided by the outer bonding wire of these a plurality of chips in fact fully.

This first and second transistor fabrication of the present invention is in single dark N trap (deep N-well).

Advantage of the present invention:

1. bigger frequency bandwidth is arranged, working range is stably arranged.

2. three independent grounding paths can effectively improve isolation effect and stability, and reduce noise.

3. the outer bonding wire of these a plurality of chips provides suitable stray inductance, and no longer needs to add inductor.

4. this first and second transistor is located in the same N trap, therefore can effectively reduce noise.

Description of drawings

Fig. 1 is the circuit diagram of conventional low noise amplifier.

Fig. 2 is the cutaway view of a chip and encapsulating structure.

Fig. 3 is the circuit diagram of the present invention's one low noise amplifier.

Fig. 4 is the curve charts of the quality factor of low noise amplifier shown in Figure 3 to frequency.

Fig. 5 is the schematic layout pattern of transistor on CMOS shown in Figure 3.

Fig. 6 is the cutaway view of transistor shown in Figure 5 on CMOS.

The reference numeral explanation

22,52,54 transistors, 24 current mirror circuits

10,50 low noise amplifiers, 12,70 ground connection

26,28,56 inductor 30CMOS chips

32 encapsulating structures, 34 chip circuit small pieces

36 chip circuit small pieces tie points, 38 bonding wires

40 outside tie point 25,58,64 resistors

60a, 60b, 60c bonding wire 62 current mirror circuits

66,68 capacitors, 80,82 curves

90 substrate 92P traps

94N trap 96 dark N traps

Embodiment

Fig. 2 is the schematic diagram of a chip 30.Chip 30 includes an encapsulating structure 32, is used for being provided with protection one chip circuit small pieces (chip die) 34.Chip circuit small pieces 34 are electrically connected to an outside tie point 40 of chip 30 by tie point 36 and bonding wire 38.Chip circuit small pieces 34 include a low noise amplifier of the present invention.Therefore, chip 30 can be installed in a printed circuit board (PCB) (PCB) or the similar device.

Fig. 3 is the circuit diagram of the present invention's one low noise amplifier 50, in Fig. 3 with dashed region in chip and outside the chip.Low noise amplifier 50 includes first and second transistor 52,54 and an inductor 56 and first resistor 58.The drain electrode of the first transistor 52 is connected to the source electrode of transistor seconds 54.The grid of the first transistor 52 be connected to RF input node, and the source electrode of the first transistor 52 is connected to a chip external ground 70.The grid of transistor seconds 54 is connected to the first bias voltage Vb1, and the drain electrode of transistor seconds 54 is connected to operating voltage Vdd via the inductor 56 and first resistor 58.One RF output signal of low noise amplifier 50 is by the drain electrode output of transistor seconds 54.

The grid of the first transistor 52 is connected to RF input node via the outer bonding wire 60a of a chip, and the source electrode of the first transistor 52 is via a bonding wire 60b ground connection.Bonding wire 38 among bonding wire 60a, 60b and Fig. 2 is similar, and the function that element in the chip is electrically connected to the chip external component is provided.According to the present invention, bonding wire 60a, 60b select suitable specification and material, so that bonding wire 60a, 60b can provide the stray inductance that meets demand, that is, the present invention does not need the inductor of chip exterior.

Low noise amplifier 50 of the present invention also includes a current mirror circuit 62, a capacitor 66 and a capacitor 68.As known to persons skilled in the art, current mirror 62 is used to produce a DC electric current, amplifies in certain proportion and forms and this DC electric current is a reference current.Current mirror circuit 62 is connected to the grid of the first transistor 52 via a biasing resistor.In current mirror circuit 62, its resistor is located between the grid of transistor gate in the current mirror circuit 62 and the first transistor 52, and these current mirror circuit 62 transistorized source grounds, drain electrode then is connected to grid.Current mirror circuit 62 receives the second bias voltage Vb2 from its included transistorized grid and drain electrode.Capacitor 66 is connected between operating voltage Vdd and the chip external ground 70.Capacitor 68 is connected between the grid of current mirror circuit 62 transistorized source electrodes and transistor seconds 54.Chip outer bonding wire 60c, 60d are used for making current mirror circuit 62 and capacitor 66 ground connection respectively.

Chip outer bonding wire 60b, 60c, 60d then provide three independently grounded circuits, have improved insulation situation and stability, and have reduced circuit noise.Replace the inductor in traditional low noise amplifier, make chip area dwindle, also can reduce manufacturing cost.

When work, a RF input signal is sent to bonding wire 60a, in the grid reception of the first transistor 52.Then, this RF input signal can be carried out amplification according to the ratio of first bias voltage Vb1 and the second bias voltage Vb2, operating voltage Vdd, 56 pairs first resistors 58 of inductor.At last, the signal that is exaggerated can be from the drain electrode output of transistor seconds 54.Generally speaking, the running of low noise amplifier 50 is approximately identical with routine techniques, is also known by those skilled in the art.This output node has capacitance, inductance value by selected this inductor 56 matches with this capacitance, so that the resonance frequency of RF output node is bigger 1.5 times than operating frequency range, wherein this electric capacity can be the parasitic capacitance of this RF output node or is general electric capacity, and it is in parallel with this capacitor 59 promptly directly to increase by a capacitor.Please refer to Fig. 4, (curve 82) and conventional low noise amplifier (curve 80) are compared according to the present invention, with under inductor 56 cooperates, can reduce quality factor (quality factor) at first resistor 58, also can improve frequency bandwidth.

For DC mode, but inductor 56 provides the path of negligible resistance, allows to have in transistor 54,52 electric current of known dimensions.And for AC mode, resistor 58 can reduce the equivalent resistance in parallel of inductor 56.

First and second transistor 52,54 of low noise amplifier 50 of the present invention is formed on the common dark N trap on the substrate.Fig. 5 is the top view that is used for making first and second transistor 52,54, and Fig. 6 is a cutaway view shown in Figure 5.On substrate 90, two P traps 92 are formed in the same N trap 94, and N trap 94 be located at a dark N trap 96 on.The making of structure shown in Fig. 5 and Fig. 6 and to be operating as those skilled in the art institute conventional is not so give unnecessary details at this.

The above only is the preferred embodiments of the present invention, and all equivalences of carrying out according to claim of the present invention change and revise, and all should belong to covering scope of the present invention.

Claims

1. low noise amplifier comprises:

The first transistor has grid, is connected to an input node; Have source electrode, be connected to the first ground connection node; Has drain electrode;

Transistor seconds has source electrode, is connected to the drain electrode of this first transistor; Have drain electrode, be connected to an output node; Have grid, be connected to first bias voltage;

One inductor is connected between this output node and the operating voltage; And

First resistor, in parallel with this inductor,

Wherein this low noise amplifier has a plurality of grounded circuits and ground connection, and each grounded circuit has stray inductance.

2. low noise amplifier as claimed in claim 1 also comprises a current mirror circuit, is connected to this input node, is used to provide a bias current.

3. low noise amplifier as claimed in claim 1, wherein, this output node has capacitance, and this capacitance can be provided by equivalent parasitic capacitances or capacitor.

4. low noise amplifier as claimed in claim 3, wherein this low noise amplifier has a resonance frequency, and its big I is determined by this inductor and this capacitance, by changing this inductor, this resonance frequency of may command.

5. low noise amplifier as claimed in claim 4, wherein this resonance frequency is bigger 1.5 times than a predetermined work frequency.

6. low noise amplifier as claimed in claim 1, wherein this low noise amplifier is formed on the substrate, and the stray inductance of these a plurality of grounded circuits is provided by the outer bonding wire of a plurality of corresponding chips in fact.

7. low noise amplifier as claimed in claim 6, wherein this first and this transistor seconds be formed in the dark N trap of this substrate.

8. low noise amplifier as claimed in claim 1, wherein this first and this transistor seconds be formed in the dark N trap of this substrate.

9. low noise amplifier as claimed in claim 1 also includes a plurality of bonding wires, in order to stray inductance to be provided.

10. one kind in order to amplify the method for an input signal, and it comprises:

Receive this input signal from an input node;

Via a plurality of independently grounded circuits, wherein respectively this grounded circuit all provides stray inductance; And amplify this input signal according to resonance frequency,

Wherein this resonance frequency is determined by the capacitance of an inductance value and an output node.

11. the method as claim 10 also comprises:

Control this inductance value, so that this resonance frequency is bigger 1.5 times than the operating frequency of this RF input signal.