CN215835381U

CN215835381U - Negative feedback adjustable gain amplification circuit

Info

Publication number: CN215835381U
Application number: CN202121353303.3U
Authority: CN
Inventors: 朱良军
Original assignee: Chengdu Weixing Technology Co ltd
Current assignee: Chengdu Weixing Technology Co ltd
Priority date: 2021-06-17
Filing date: 2021-06-17
Publication date: 2022-02-15
Anticipated expiration: 2031-06-17

Abstract

The utility model discloses a negative feedback adjustable gain amplification circuit, and belongs to the technical field of radio signal amplification. The amplifier comprises an amplifier A1, wherein a pin 1 of the amplifier A1 is connected with a first end of a current-limiting resistor R2, and a second end of the amplifier A1 is respectively connected with a power supply VCC, a second end of a current-limiting resistor R3, a second end of the current-limiting resistor R4 and a first end of a decoupling capacitor C6; a pin 5 of the amplifier A1 is connected with a first end of a current-limiting resistor R4, a pin 6 is connected with a first end of a current-limiting resistor R3, and a first end of a decoupling capacitor C6 is also respectively connected with a second end of the current-limiting resistor R3 and a second end of a current-limiting resistor R4; the 3 pins of the amplifier A1 are respectively connected with the input matching network circuit and the negative feedback network circuit, and the 4 pins of the amplifier A1 are connected with the output matching network circuit; the negative feedback network circuit comprises an adjustable resistor RT and an adjustable capacitor CT. The amplifying circuit of the utility model adopts a negative feedback mode to adjust the gain, can flexibly adjust the gain of the amplifier and obviously improve the noise of an amplifying link and the third-order intermodulation.

Description

Negative feedback adjustable gain amplification circuit

Technical Field

The utility model belongs to the technical field of radio signal amplification, and particularly relates to a negative feedback adjustable gain amplification circuit.

Background

In the reception processing of radio signals, amplification of the radio signals is essential. In the radio signal amplification process, noise, gain and third-order intermodulation are important indexes for measuring the performance of an amplification link. The smaller the noise, the higher the sensitivity of the received signal, so the smaller the amplification link noise, the better; the gain of the amplifying link needs to be matched with the receiving processing circuit, the gain is too small, the intensity of a radio signal input to the receiving processing circuit is too low, the receiving processing circuit cannot effectively receive a useful signal, so that the radio signal cannot be normally processed, the gain of the amplifying link is too high, the third-order intermodulation is too low, so that the adjacent frequency interference is too strong, and the receiving processing circuit cannot effectively receive the useful signal. The gain and noise of the amplifier adopted by the existing amplifying chain are fixed, the sum of the gain of the amplifier must be higher than the gain of the required amplifying chain, and then the sum of the gain of the amplifier is adjusted to the gain of the required amplifying chain by using a resistance attenuator. By the method, the link noise is amplified, the third-order intermodulation cannot be optimized, and the performance of the amplification link cannot be improved.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a negative feedback adjustable gain amplification circuit, which can flexibly adjust the gain of an amplifier and obviously improve the noise of an amplification link and third-order intermodulation.

In order to achieve the purpose, the technical scheme of the utility model is as follows: a negative feedback adjustable gain amplifying circuit comprises an amplifier A1, wherein a pin 1 of the amplifier A1 is connected with a first end of a current-limiting resistor R2, and a second end of the current-limiting resistor R2 is respectively connected with a power supply VCC, a second end of a current-limiting resistor R3, a second end of a current-limiting resistor R4 and a first end of a decoupling capacitor C6; a pin 5 of the amplifier A1 is connected with a first end of a current-limiting resistor R4, a pin 6 of the amplifier A1 is connected with a first end of a current-limiting resistor R3, and a first end of the decoupling capacitor C6 is also respectively connected with a second end of a current-limiting resistor R3 and a second end of a current-limiting resistor R4; the second end of the decoupling capacitor C6 is grounded, 3 pins of the amplifier A1 are respectively connected with an input matching network circuit and a negative feedback network circuit, and 4 pins of the amplifier A1 are connected with an output matching network circuit;

negative feedback network circuit includes adjustable resistance RT and adjustable electric capacity CT, the first end of adjustable electric capacity CT is connected to amplifier A1's 3 pins, the first end of adjustable resistance RT is connected to adjustable electric capacity CT's second end, the second end of inductance L4 is connected to adjustable resistance RT's second end.

Further, the output matching network circuit comprises a blocking capacitor C3, a capacitor C4, an inductor L2, an inductor L3 and an inductor L4, wherein a first end of the inductor L4 is connected with a 4-pin of an amplifier a1, a second end of the inductor L4 is respectively connected with a second end of an adjustable resistor RT, a high-frequency signal isolation circuit and a first end of the blocking capacitor C3, a second end of the blocking capacitor C3 is respectively connected with a first end of the inductor L2 and a first end of the capacitor C4, a second end of the capacitor C4 is grounded, a second end of the inductor L2 is respectively connected with a first end and an RF output end of the inductor L3, and a second end of the inductor L3 is grounded.

Further, the input matching network circuit comprises an inductor L5, an inductor L6, a capacitor C5, a capacitor C7 and a dc blocking capacitor C8, a pin 3 of the amplifier a1 is connected to a first end of the inductor L5, a second end of the inductor L5 is respectively connected to a first end of the capacitor C5 and a first end of the inductor L6, a second end of the capacitor C5 is grounded, a second end of the inductor L6 is respectively connected to a first end of the capacitor C7 and a first end of the capacitor C8, a second end of the capacitor C7 is grounded, and a second end of the capacitor C8 is connected to an RF input signal.

Further, the high-frequency signal isolation circuit comprises a choke inductor L1, a decoupling capacitor C2 and a decoupling capacitor C1, wherein the second end of the choke inductor L1 is respectively connected with the first end of the decoupling capacitor C2, the first end of the decoupling capacitor C1 and the first end of a current-limiting resistor R1, the second end of the decoupling capacitor C2 and the second end of the decoupling capacitor C1 are both grounded, and the second end of the current-limiting resistor R1 is connected with a power supply VCC.

Further, the amplifier a1 adopts an amplifier with the model number BGU 6101.

Further, the voltage of the power source VCC is 3V.

Further, pins 7, 8, 9 and 10 of the amplifier a1 are all grounded, and pin 2 of the amplifier a1 is floating.

Due to the adoption of the technical scheme, the utility model has the beneficial effects that: the amplifying circuit of the utility model adopts a negative feedback mode to adjust the gain, can flexibly adjust the gain of the amplifier and obviously improve the noise of an amplifying link and the third-order intermodulation.

Drawings

FIG. 1 is a circuit block diagram of the present invention;

the labels in the figure are: 1-input matching network circuit; 2-output matching network circuit; 3-a high frequency signal isolation circuit; 4-negative feedback network circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the present embodiment discloses a negative feedback adjustable gain amplification circuit, which includes an amplifier a1, a pin 1 of the amplifier a1 is connected to a first end of a current limiting resistor R2, and a second end of the current limiting resistor R2 is connected to a power supply VCC, a second end of the current limiting resistor R3, a second end of the current limiting resistor R4, and a first end of a decoupling capacitor C6, respectively; a pin 5 of the amplifier A1 is connected with a first end of the current-limiting resistor R4, a pin 6 of the amplifier A1 is connected with a first end of the current-limiting resistor R3, and a first end of the decoupling capacitor C6 is also respectively connected with a second end of the current-limiting resistor R3 and a second end of the current-limiting resistor R4; the second end of the decoupling capacitor C6 is grounded, 3 pins of the amplifier A1 are respectively connected with the input matching network circuit 1 and the negative

feedback network circuit

4, and 4 pins of the amplifier A1 are connected with the output matching network circuit 2; the negative feedback network circuit 4 comprises an adjustable resistor RT and an adjustable capacitor CT, wherein a pin 3 of the amplifier A1 is connected with a first end of the adjustable capacitor CT, a second end of the adjustable capacitor CT is connected with a first end of the adjustable resistor RT, and a second end of the adjustable resistor RT is connected with a second end of the inductor L4.

Further, the output matching network circuit 2 of the present embodiment includes a dc blocking capacitor C3, a capacitor C4, an inductor L2, an inductor L3, and an inductor L4, wherein a first end of the inductor L4 is connected to the 4 pins of the amplifier a1, a second end of the inductor L4 is connected to the second end of the adjustable resistor RT, the high-frequency signal isolation circuit 3, and the first end of the dc blocking capacitor C3, a second end of the dc blocking capacitor C3 is connected to the first end of the inductor L2 and the first end of the capacitor C4, a second end of the capacitor C4 is grounded, a second end of the inductor L2 is connected to the first end of the inductor L3 and the RF output terminal, and a second end of the inductor L3 is grounded.

Further, the input matching network circuit 1 of the present embodiment includes an inductor L5, an inductor L6, a capacitor C5, a capacitor C7, and a dc blocking capacitor C8, wherein a pin 3 of the amplifier a1 is connected to a first end of the inductor L5, a second end of the inductor L5 is respectively connected to a first end of the capacitor C5 and a first end of the inductor L6, a second end of the capacitor C5 is grounded, a second end of the inductor L6 is respectively connected to a first end of the capacitor C7 and a first end of the capacitor C8, a second end of the capacitor C7 is grounded, and a second end of the capacitor C8 is connected to the RF input signal.

Further, the high-frequency signal isolation circuit 3 of the present embodiment includes a choke inductor L1, a decoupling capacitor C2, and a decoupling capacitor C1, wherein a second terminal of the choke inductor L1 is connected to a first terminal of the decoupling capacitor C2, a first terminal of the decoupling capacitor C1, and a first terminal of a current limiting resistor R1, a second terminal of the decoupling capacitor C2 and a second terminal of the decoupling capacitor C1 are both grounded, and a second terminal of the current limiting resistor R1 is connected to the power VCC.

Further, the amplifier a1 of the present embodiment is an amplifier of the type BGU 6101.

Further, the voltage of the power supply VCC is 3V.

Further, the pins 7, 8, 9 and 10 of the amplifier a1 of the present embodiment are all grounded, and the pin 2 of the amplifier a1 is floating.

In the specific work, the working principle of the utility model is as follows: the DC blocking capacitor C8 and the DC blocking capacitor C3 isolate the DC bias voltage of 3 pins of the amplifier A1, an RF signal is loaded to the 3 pins of the amplifier A1 through an input matching network consisting of the capacitor C5, the capacitor C7, an inductor L5 and an inductor L6, the amplifier A1 amplifies the RF signal and outputs the amplified RF signal through an output matching network consisting of the inductor L4, the capacitor C4, the inductor L2 and the inductor L3; the inductor L1 is a choke inductor, and forms a high-frequency signal isolation network circuit together with the decoupling capacitor C1 and the decoupling capacitor C2, the current-limiting resistor R1 adjusts the bias voltage loaded on the 4 pins of the amplifier A1 by the power supply VCC, and the current-limiting resistor R3 adjusts the working current of the amplifier A1; the current limiting resistor R2 and the current limiting resistor R4 are overvoltage protection resistors, which play a role in overvoltage protection of the amplifier A1, the adjustable resistor RT and the adjustable capacitor CT together form a negative feedback network circuit, shunt the RF signal to the negative feedback network circuit, and deflecting the phase of the shunted negative feedback RF signal, the phase difference between the deflected negative feedback signal and the input RF signal at the 3 pin terminal of the amplifier A1 being greater than 90 DEG, the negative feedback signal and the input RF signal forming a vector sum at the 3 pin terminal of the amplifier A1, the feedback coefficient F is 1/RT multiplied by CT (F is less than 1), the closed loop gain G of the negative feedback amplifying circuit is A.F, the closed loop noise No is Ni.F, the feedback coefficient can be changed by adjusting the value of the resistance RT or the adjustable capacitance CT, thereby changing the closed loop gain of the amplifier, the negative feedback amplifier closed loop gain is reduced by a-A.F from the open loop gain, and the third order intermodulation is reduced by 2 (a-A.F). In the whole amplification link, compared with the mode that the gain of the amplifier is directly adjusted by the resistance attenuator, the gain of the amplifier is adjusted by negative feedback, the noise is reduced by Ni-No, the third-order intermodulation is reduced by A-A.F, and the performance of the whole amplification link is obviously improved. In this embodiment, a is the amplifier open-loop gain, F is the feedback coefficient, Ni is the amplifier open-loop noise, and No is the amplifier closed-loop noise.

The scope of the present invention includes, but is not limited to, the above embodiments, and the present invention is defined by the appended claims, and any alterations, modifications, and improvements that may occur to those skilled in the art are all within the scope of the present invention.

Claims

1. A negative feedback adjustable gain amplification circuit comprising an amplifier a1, wherein: a pin 1 of the amplifier A1 is connected with a first end of a current-limiting resistor R2, and a second end of the current-limiting resistor R2 is respectively connected with a power supply VCC, a second end of the current-limiting resistor R3, a second end of the current-limiting resistor R4 and a first end of a decoupling capacitor C6; a pin 5 of the amplifier A1 is connected with a first end of a current-limiting resistor R4, a pin 6 of the amplifier A1 is connected with a first end of a current-limiting resistor R3, a first end of the decoupling capacitor C6 is also respectively connected with a second end of a current-limiting resistor R3 and a second end of a current-limiting resistor R4, and a second end of the decoupling capacitor C6 is grounded;

the amplifier further comprises an input matching network circuit (1), a negative feedback network circuit (4) and an output matching network circuit (2), wherein 3 pins of the amplifier A1 are respectively connected with the input matching network circuit (1) and the negative feedback network circuit (4), and 4 pins of the amplifier A1 are connected with the output matching network circuit (2); negative feedback network circuit (4) include adjustable resistance RT and adjustable electric capacity CT, the first end of adjustable electric capacity CT is connected to amplifier A1's 3 pins, the first end of adjustable resistance RT is connected to adjustable electric capacity CT's second end, the second end of adjustable resistance RT connects the second end of inductance L4.

2. The negative feedback adjustable gain amplifier circuit of claim 1, wherein: the output matching network circuit (2) comprises a blocking capacitor C3, a capacitor C4, an inductor L2, an inductor L3 and an inductor L4, wherein a first end of the inductor L4 is connected with a 4-pin of an amplifier A1, a second end of the inductor L4 is respectively connected with a second end of an adjustable resistor RT, a high-frequency signal isolation circuit (3) and a first end of the blocking capacitor C3, a second end of the blocking capacitor C3 is respectively connected with a first end of the inductor L2 and a first end of the capacitor C4, a second end of the capacitor C4 is grounded, a second end of the inductor L35 2 is respectively connected with a first end of the inductor L3 and an RF output end, and a second end of the inductor L3 is grounded.

3. The negative feedback adjustable gain amplifier circuit of claim 1, wherein: the input matching network circuit (1) comprises an inductor L5, an inductor L6, a capacitor C5, a capacitor C7 and a blocking capacitor C8, wherein a pin 3 of the amplifier A1 is connected with a first end of the inductor L5, a second end of the inductor L5 is respectively connected with a first end of the capacitor C5 and a first end of the inductor L6, a second end of the capacitor C5 is grounded, a second end of the inductor L6 is respectively connected with a first end of the capacitor C7 and a first end of the capacitor C8, a second end of the capacitor C7 is grounded, and a second end of the capacitor C8 is connected with an RF input signal.

4. The negative feedback adjustable gain amplifier circuit of claim 2, wherein: the high-frequency signal isolation circuit (3) comprises a choke inductor L1, a decoupling capacitor C2 and a decoupling capacitor C1, wherein the second end of the choke inductor L1 is respectively connected with the first end of the decoupling capacitor C2, the first end of the decoupling capacitor C1 and the first end of a current-limiting resistor R1, the second end of the decoupling capacitor C2 and the second end of the decoupling capacitor C1 are both grounded, and the second end of the current-limiting resistor R1 is connected with a power supply VCC.

5. The negative feedback adjustable gain amplifier circuit of claim 1, wherein: the amplifier A1 is an amplifier with the model number BGU 6101.

6. The negative feedback adjustable gain amplifier circuit of claim 1, wherein: the voltage of the power supply VCC is 3V.

7. The negative feedback adjustable gain amplifier circuit of claim 1, wherein: the 7 pin, 8 pin, 9 pin and 10 pin of the amplifier A1 are all grounded, and the 2 pin of the amplifier A1 is floating.