CN101425780B

CN101425780B - Low Noise Broadband Amplifier Circuit

Info

Publication number: CN101425780B
Application number: CN2007100941950A
Authority: CN
Inventors: 赵春; 魏述然
Original assignee: RDA Technologies Ltd
Current assignee: RDA MICROELECTRONICS CO Ltd
Priority date: 2007-11-02
Filing date: 2007-11-02
Publication date: 2011-06-08
Anticipated expiration: 2027-11-02
Also published as: CN101425780A

Abstract

The invention discloses a low-noise broadband amplifier circuit, which comprises a first-stage circuit and a second-stage circuit, wherein the first-stage circuit comprises two inverters, two ends of a differential input signal are respectively connected to input ends of the two inverters, the second-stage circuit also comprises two inverters, output ends of the two inverters of the first-stage circuit are respectively connected to input ends of the two inverters of the second-stage circuit, the first-stage circuit and the second-stage circuit are isolated by adopting a current source, a current source is also isolated between the second-stage circuit and a power supply, and output ends of the two inverters of the second-stage circuit are output ends of the low-noise broadband amplifier circuit. The invention adopts a two-stage structure of current multiplexing, has good stability and high gain performance, simultaneously greatly reduces the power consumption, has the effect of resisting the back kicking of a rear load circuit by a second-stage circuit, and realizes higher gain.

Description

Low-noise wide-band amplifier circuit

Technical field

The present invention relates to a kind of circuit, especially a kind of low-noise wide-band amplifier circuit.

Background technology

Low-noise wide-band amplifier circuit is a root module before the radio frequency chip, requires to have low noise, high bandwidth, high linearity, high-gain, low in power consumption, is used in the technical scheme of FM demodulator, TV demodulator, UWB or other wide band radio-frequencies more.In existing low-noise wide-band amplifier (LNA) circuit arrangement, more common has three kinds:

Circuit shown in Figure 1 is for having common grid input structure low-noise wide-band amplifier circuit, include a NMOS pipe, the grid of this NMOS pipe is connected with bias voltage Vbias, drain electrode is connected to power end by a variable resistor Rload, source electrode is by resistance R s ground connection, the end that described resistance R s is connected with source electrode is as signal input part, and described drain electrode is as signal output part.

Circuit shown in Figure 2 is the common-source amplifier circuit with input resistance in parallel, include a NMOS pipe, the drain electrode of this metal-oxide-semiconductor is connected to power end by a variable resistor Rload, the direct ground connection of source electrode, grid connects input signal by a resistance R, also by a resistance R s ground connection, described drain electrode is as signal output part for described grid.

Circuit shown in Figure 3 is the low-noise wide-band amplifier circuit with string and feedback arrangement, include a NMOS pipe, the grid of this NMOS pipe connects input signal by a resistance R, be connected with resistance R _ f between described grid and the drain electrode, drain electrode is connected to power end by a variable resistor Rload, source electrode is by resistance R s ground connection, and described drain electrode is as signal output part.

The shortcoming that three kinds of above-mentioned existing low-noise wide-band amplifier circuits generally have is: noise factor is big, power consumption is big, the anti-anti-ability of playing, the more and more requirement of incompatibility technical development.

Summary of the invention

Technical problem to be solved by this invention provides a kind of low-noise wide-band amplifier circuit, can solve the contradiction between the indexs such as bandwidth, low noise, high linearity, make low-noise wide-band amplifier circuit have the anti-performance of playing of good noise factor, low-power consumption, high linearity, wideband impedance match and anti-load circuit simultaneously.

For solving the problems of the technologies described above, the technical scheme of low-noise wide-band amplifier circuit of the present invention is, comprise first order circuit and second level circuit, described first order circuit comprises two phase inverters, the two ends of differential input signal are connected respectively to the input of described two phase inverters, described second level circuit also comprises two phase inverters, the output of two phase inverters of described first order circuit is connected respectively to the input of two phase inverters of described second level circuit, adopt current source to isolate between described first order circuit and the described second level circuit, also isolating between described second level circuit and the power supply has current source, and the output of two phase inverters of described second level circuit is the output of low-noise wide-band amplifier circuit.

The present invention adopts the two-layer configuration of current multiplexing, and each grade all adopt the phase inverter (inverter) of two symmetries, has good stability and high-gain performance, and power consumption reduces greatly simultaneously; Adopt self-bias current source to isolate between the first order and the second level, has good isolation effect, make the second level have the effect that single-ended input slip divides output simultaneously, also there is the anti-effect of playing of anti-back load circuit the second level, has avoided the chip internal radio noise to be input to antenna end from amplifier circuit and has let out; Because amplifier circuit has adopted secondary structure, so also realized higher gain.

Description of drawings

The present invention is further detailed explanation below in conjunction with drawings and Examples:

Fig. 1, Fig. 2 and Fig. 3 are the circuit diagram of existing low-noise wide-band amplifier circuit;

Fig. 4 is the circuit diagram of low-noise wide-band amplifier circuit of the present invention;

Fig. 5 is the circuit diagram of a kind of embodiment of low-noise wide-band amplifier circuit of the present invention;

Fig. 6 is the circuit diagram of the voltage offset electric circuit that current source connected of circuit among Fig. 5.

Embodiment

As shown in Figure 4, low-noise wide-band amplifier circuit of the present invention, comprise first order circuit and second level circuit, described first order circuit comprises two phase inverters, the two ends of differential input signal are connected respectively to the input INP and the INN of described two phase inverters, described second level circuit also comprises two phase inverters, the output of two phase inverters of described first order circuit is connected respectively to the input of two phase inverters of described second level circuit, adopt current source to isolate between described first order circuit and the described second level circuit, also isolating between described second level circuit and the power supply has current source, and the output VOP of two phase inverters of described second level circuit and VON are the output of low-noise wide-band amplifier circuit.

Be provided with coupling capacitance C3 and C4 between the input of the output of described first order circuit and described second level circuit; Also be provided with coupling capacitance C1 and C2 between the input of described differential input signal and described first order circuit.

Described phase inverter comprises a NMOS pipe and a PMOS pipe, as the MP1 among Fig. 4, MN1, MP2, MN2, MP3, MN3, MP4 and MN4, the grid of described NMOS pipe is connected with the grid of described PMOS pipe, the drain electrode of described NMOS pipe is connected with the drain electrode of described PMOS pipe, be connected with variable resistor between the grid of described NMOS pipe and PMOS pipe and the drain electrode, as the R1 among Fig. 4, R2, R3 and R4, the grid of described NMOS pipe and PMOS pipe is the input of described phase inverter, and the drain electrode of described NMOS pipe and PMOS pipe is the output of described phase inverter; In first order circuit, the source electrode of two PMOS pipe MP1 and MP2 is connected, and the source electrode of two NMOS pipe MN1 and MN2 is connected and ground connection; In the circuit of the second level, the source electrode of two PMOS pipe MP3 and MP4 is connected, and the source electrode of two NMOS pipe MN3 and MN4 is connected; Between the source electrode that the current source of isolating between described first order circuit and the described second level circuit is arranged on described first order circuit PMOS pipe MP1 and MP2 and the source electrode MN3 and MN4 of described second level circuit NMOS pipe, the current source between described second level circuit and the power supply is arranged between the source electrode and power supply that described second level circuit PMOS manages MP3 and MP4.

In low-noise wide-band amplifier circuit of the present invention, the phase inverter that constitutes with MP1 and MN1 is an example, and variable resistor R1 is used for regulating gain, and has realized automatic biasing, makes two metal-oxide-semiconductors of MP1 and MN1 all be operated in the saturation region.The amplifier gain is (gmn+gmp) * R1, so its input impedance by electric current and device size rationally are set, makes input impedance equal characteristic impedance for 1/ fixing (gmn+gmp), realizes the wideband impedance match under the high-gain situation.

Because the common mode terminal of PMOS pipe and NMOS pipe is current source, divide the effect of output so also realized single-ended input slip simultaneously.Variable resistor R3 and R4 provide dc offset voltage when regulating gain, guaranteed stability of structure.

As shown in Figure 5, current source between described first order circuit and the second level circuit comprises a NMOS pipe MN5, the grid of this NMOS pipe MN5 is connected with bias voltage VBIAS, the drain electrode of this NMOS pipe MN5 is connected to the source electrode of described second level circuit NMOS pipe MN3 and MN4, and the source electrode of this NMOS pipe MN5 is connected to the source electrode of described first order circuit PMOS pipe MP1 and MP2.

Above-mentioned current source is simple in structure, and owing to be automatic biasing, so the size of current of current source up and down of second level circuit is mated fully, and matching is not influenced by process deviation, the node p1 of source class place of MN5 pipe is the low-resistance point, good restraining crosstalking between first order circuit and the second level circuit.

As shown in Figure 6, described bias voltage VBIAS is provided by a voltage offset electric circuit, the bias voltage output of described voltage offset electric circuit connects an end of three resistance R 5, R6, R7 and a capacitor C 5 respectively, in conjunction with Fig. 4 and shown in Figure 5, the other end of described resistance R 5 is connected to an output VOP of described second level circuit, the other end of described resistance R 6 is connected to another output VON of described second level circuit, and the other end of the other end of described resistance R 7 and described capacitor C 5 all is connected to the node p1 of the source electrode of pipe MP1 of PMOS in the described first order circuit and MP2.

The total of low-noise wide-band amplifier circuit provided by the present invention is divided into two-stage, and the first order and the second level realized current multiplexing, greatly reduces power consumption, has improved performance; Because amplifier adopts the structure of automatic biasing, so structure is also very stable, linearity height; Input impedance is only relevant with the input stage feature, not influenced by operating frequency range, has realized the input impedance matching of wide frequency ranges; Support single-ended input pattern, when having only single-ended signal to come in, the another one input only needs ground connection getting final product; Be output as differential signal, noise has been realized good restraining.

Claims

1. A low-noise broadband amplifier circuit, characterized in that, comprises a first-stage circuit and a second-stage circuit, the first-stage circuit includes two inverters, and the two ends of the differential input signal are respectively connected to the two The input terminals of an inverter, the second stage circuit also includes two inverters, and the output terminals of the two inverters of the first stage circuit are respectively connected to the two inverters of the second stage circuit The input end of the phase converter, the first stage circuit is isolated from the second stage circuit by a current source, and a current source is also isolated between the second stage circuit and the power supply, and the two stages of the second stage circuit The output terminal of each inverter is the output terminal of the low noise broadband amplifier circuit.

2. low-noise broadband amplifier circuit according to claim 1, is characterized in that, is provided with coupling capacitance between the output end of described first stage circuit and the input end of described second stage circuit; Described differential input signal A coupling capacitor is also provided between the input terminal of the first stage circuit.

3. The low-noise broadband amplifier circuit according to claim 1, wherein the inverter comprises an NMOS transistor and a PMOS transistor, and the grid of the NMOS transistor is connected to the grid of the PMOS transistor , the drain of the NMOS transistor is connected to the drain of the PMOS transistor, a variable resistor is connected between the gate and the drain of the NMOS transistor and the PMOS transistor, and the gates of the NMOS transistor and the PMOS transistor are The input terminal of the inverter, the drain of the NMOS transistor and the PMOS transistor are the output terminals of the inverter; in the first stage circuit, the sources of the two PMOS transistors are connected, and the drains of the two NMOS transistors The sources are connected and grounded; in the second stage circuit, the sources of the two PMOS transistors are connected, and the sources of the two NMOS transistors are connected; the first stage circuit is isolated from the second stage circuit The current source is set between the source of the first-stage circuit PMOS transistor and the source of the second-stage circuit NMOS transistor, and the current source between the second-stage circuit and the power supply is set in the second Between the source of the stage circuit PMOS tube and the power supply.

4. The low-noise broadband amplifier circuit according to claim 3, wherein the current source between the first stage circuit and the second stage circuit comprises an NMOS transistor, and the gate of the NMOS transistor is connected with a bias voltage, the drain of the NMOS transistor is connected to the source of the NMOS transistor of the second stage circuit, and the source of the NMOS transistor is connected to the source of the PMOS transistor of the first stage circuit.

5. The low-noise broadband amplifier circuit according to claim 4, wherein the bias voltage is provided by a voltage bias circuit, and the bias voltage output terminals of the voltage bias circuit are respectively connected to three resistors R5 , R6, R7 and one end of a capacitor C5, the other end of the resistor R5 is connected to an output end of the second stage circuit, and the other end of the resistor R6 is connected to the other output of the second stage circuit end, the other end of the resistor R7 and the other end of the capacitor C5 are both connected to the source of the PMOS transistor in the first stage circuit.