A circuit structure for adjusting the amplitude of a closed-loop gain signal

Abstract

The utility model relates to signal processing circuit, specifically relates to a circuit structure of adjustable closed loop gain signal amplitude, the power input end of operational amplifier U2, U4 all are connected with current switch U5, the output of operational amplifier U2, U4 all are connected with resistance array U6, the same phase input end of operational amplifier U2 is grounded, and the opposite phase input end is connected with the opposite phase input end of operational amplifier U4, resistance array U6, the same phase input end of operational amplifier U4 is connected with resistance array U6, the opposite phase input end of comparator U3 is grounded, and the same phase input end is connected signal input square wave, and the output of comparator U3 is as the input of current switch U5, controls the output end of operational amplifier U2 or U4 and is connected with resistance array U6, and the output corresponding closed loop gain signal amplitude's waveform is adjusted. Compared with prior modem, the utility model discloses more simple structure, and through resistance array U6 can realize the adjustment of different amplitude signal.

Description

Technical Field

[0001] This utility model relates to signal processing circuits, specifically to a circuit structure with adjustable closed-loop gain signal amplitude. Background Technology

[0002] With the continuous advancement of communication technology, the requirements for signal processing are increasing. Modems are widely used in communication products, and various products involving signal processing cannot function without modems.

[0003] Most current modem patents focus on signal frequency regulation and control. For example, Chinese patent application CN110012181A discloses a "timing controller, modem chip and integrated circuit including the same," which configures a processor to generate instructions; a timing controller configured to generate control signals corresponding to the instructions at the execution time of the instructions; the timing controller includes: a heap sorting circuit configured to sort the instructions using the execution time, based on heap sort, and according to the execution order of the instructions; a reference counter configured to generate a reference time; and a signal generator configured to generate a control signal corresponding to the current instruction when the reference time matches the execution time of the current instruction with the highest execution order among the instructions.

[0004] However, this type of modem has many circuit modules and a very complex structure. Utility Model Content

[0005] The purpose of this invention is to solve the technical problems of complex structure and simple amplitude modulation function in existing modems, and to provide a circuit structure with adjustable closed-loop gain signal amplitude.

[0006] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows:

[0007] A circuit structure with adjustable closed-loop gain signal amplitude includes a bandgap reference source circuit U1 and a resistor array U6, as well as operational amplifiers U2 and U4, a comparator U3 and a current switch U5 connected to the bandgap reference source circuit U1.

[0008] The power input terminals of operational amplifiers U2 and U4 are both connected to current switch U5; the output terminals of operational amplifiers U2 and U4 are both connected to resistor array U6.

[0009] The non-inverting input terminal of the operational amplifier U2 is grounded, and the inverting input terminal is connected to the inverting input terminal of the operational amplifier U4 and the resistor array U6; the non-inverting input terminal of the operational amplifier U4 is connected to the resistor array U6.

[0010] The inverting input of comparator U3 is grounded, and the non-inverting input is connected to a square wave signal input. The output of comparator U3 is connected to current switch U5. The output of comparator U3 serves as the input of current switch U5, controlling the output of operational amplifier U2 or U4 to connect to resistor array U6, and outputting the waveform of the corresponding closed-loop gain signal amplitude.

[0011] Furthermore, the current switch includes bipolar transistors Q1, Q2, Q3, and Q4;

[0012] The bases of the bipolar transistors Q1, Q2, Q3 and Q4 are all connected to the output of comparator U3;

[0013] The emitters of bipolar transistors Q1 and Q3 are connected, and are connected to the constant current source I1 of the bandgap reference source circuit U1; the emitters of bipolar transistors Q2 and Q4 are connected, and are connected to the constant current source I2 of the bandgap reference source circuit U1.

[0014] The collectors of bipolar transistors Q1 and Q2 are connected to operational amplifier U4, and the collectors of bipolar transistors Q3 and Q4 are connected to operational amplifier U2.

[0015] Furthermore, the resistor array U6 is connected to the output terminals of operational amplifiers U2 and U4 via a single-pole four-throw switch.

[0016] Furthermore, the resistor array U6 includes resistors R1, R3, R5 and R7 respectively connected to the four throws of the single-pole four-throw switch, and R2, R4, R6 and R8 respectively connected to one end of resistors R1, R3, R5 and R7.

[0017] The blade of the single-pole four-throw switch is connected to the output terminals of operational amplifiers U2 and U4;

[0018] The inverting input terminals of operational amplifiers U2 and U4, the non-inverting input terminal of operational amplifier U4, are connected to the junctions of resistors R1 and R2, resistors R3 and R4, resistors R5 and R6, or resistors R7 and R8.

[0019] Furthermore, the resistors R1, R2, R3, R4, R5, R6, R7 and R8 are all metal thin film resistors, and their resistance values ​​are 2.5K, 2.5K, 5K, 5K, 10K, 10K, 1K and 1K, respectively.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] 1. The circuit structure of the adjustable closed-loop gain signal amplitude provided by this utility model controls the operation amplifiers U2 and U4 to turn on or off through comparator U3 and current switch U5 to output different signals. At the same time, the output signal can be amplitude modulated through resistor array U6. Moreover, compared with existing modems, the structure is simpler and the resistor array U6 can be used to adjust the signal amplitude.

[0022] 2. The circuit structure for adjustable closed-loop gain signal amplitude provided by this utility model can significantly improve the closed-loop gain accuracy and achieve adjustment and control of different gains by changing the resistance value of the resistors in the resistor array U6 or changing the connection method between the operational amplifiers U2 and U4 and the resistors in the resistor array U6. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model;

[0024] Figure 2 This is a schematic diagram of the structure of operational amplifiers U2 and U4, comparator U3 and current switch U5 in the embodiment of this utility model;

[0025] Figure 3 This is a schematic diagram of the structure of an embodiment of the present utility model;

[0026] Figure 4 This is a waveform diagram of the output signal of an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0028] like Figure 1 As shown, a circuit structure with adjustable closed-loop gain signal amplitude includes a bandgap reference source circuit U1 and a resistor array U6, as well as operational amplifiers U2 and U4, a comparator U3 and a current switch U5 connected to the bandgap reference source circuit U1.

[0029] The bandgap reference source circuit U1 is used to output a PTAT current with a positive temperature coefficient;

[0030] The power input terminals of operational amplifiers U2 and U4 are both connected to current switch U5; the output terminals of operational amplifiers U2 and U4 are both connected to resistor array U6.

[0031] The non-inverting input of operational amplifier U2 is grounded, and its inverting input is connected to the inverting input of operational amplifier U4 and resistor array U6; the non-inverting input of operational amplifier U4 is connected to resistor array U6.

[0032] The inverting input of comparator U3 is grounded, and the non-inverting input is connected to a square wave signal input. The output of comparator U3 is connected to the current switch U5. The output of comparator U3 serves as the input of the current switch U5, controlling the output of operational amplifier U2 or U4 to connect to the resistor array U6, thus outputting the waveform of the corresponding closed-loop gain signal amplitude.

[0033] like Figure 2 As shown, the current switch includes bipolar transistors Q1, Q2, Q3 and Q4; the bases of bipolar transistors Q1, Q2, Q3 and Q4 are all connected to the output of comparator U3;

[0034] The emitters of bipolar transistors Q1 and Q3 are connected, and are also connected to the constant current source I1 of the bandgap reference source circuit U1; the emitters of bipolar transistors Q2 and Q4 are connected, and are also connected to the constant current source I2 of the bandgap reference source circuit U1.

[0035] The collectors of bipolar transistors Q1 and Q2 are connected to operational amplifier U4, and the collectors of bipolar transistors Q3 and Q4 are connected to operational amplifier U2.

[0036] like Figure 1 As shown, resistor array U6 is connected to the output terminals of operational amplifiers U2 and U4 via a single-pole four-throw switch.

[0037] like Figure 1 As shown, the resistor array U6 includes resistors R1, R3, R5 and R7 that are respectively connected to the four throws of the single-pole four-throw switch, and R2, R4, R6 and R8 that are respectively connected to one end of resistors R1, R3, R5 and R7.

[0038] The blade of the single-pole four-throw switch is connected to the output terminals of operational amplifiers U2 and U4;

[0039] The inverting input terminals of operational amplifiers U2 and U4, the non-inverting input terminal of operational amplifier U4, are connected to the junctions of resistors R1 and R2, resistors R3 and R4, resistors R5 and R6, or resistors R7 and R8.

[0040] Resistors R1, R2, R3, R4, R5, R6, R7, and R8 are all metal film resistors with resistance values ​​of 2.5K, 2.5K, 5K, 5K, 10K, 10K, 1K, and 1K, respectively. By employing different connection methods, the closed-loop gain can be adjusted to ±1, ±2, ±4, or other configurations, thereby achieving different amplitude waveforms for the input signal output.

[0041] like Figure 3 As shown, in this embodiment, the values ​​of resistors R1, R2, R3, R4, R5 and R6 in resistor array U6 are 2.5K, 2.5K, 10K, 5K, 10K and 5K, respectively;

[0042] The inverting input terminals of operational amplifiers U2 and U4 are connected to the junction of resistors R5 and R6, and the non-inverting input terminal of operational amplifier U4 is connected to the junction of resistors R1 and R2.

[0043] The other ends of resistors R2 and R6 are connected to the modulation signal input / output terminals, such as... Figure 4 As shown.

[0044] exist Figure 4 In the diagram, the green square wave and the purple sine wave are the input waves. The green square wave is a square wave with a given frequency, and the waveform at the non-inverting input MP of comparator U3 is input (INPUT_2). The purple sine wave is a sine wave with a given frequency, and the waveform at the operational amplifier U4 is input (INPUT_1).

[0045] The red wave is the output wave (OUT). The comparator output controls the current switch to regulate the operation amplifier's opening and closing, thereby achieving + / -2 times gain switching and amplitude modulation switching of the input sine wave waveform.

[0046] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A circuit structure with adjustable closed-loop gain signal amplitude, characterized in that: It includes a bandgap reference source circuit U1 and a resistor array U6, as well as operational amplifiers U2 and U4, comparator U3 and current switch U5 connected to the bandgap reference source circuit U1; The power input terminals of operational amplifiers U2 and U4 are both connected to current switch U5; the output terminals of operational amplifiers U2 and U4 are both connected to resistor array U6. The non-inverting input terminal of the operational amplifier U2 is grounded, and the inverting input terminal is connected to the inverting input terminal of the operational amplifier U4 and the resistor array U6; the non-inverting input terminal of the operational amplifier U4 is connected to the resistor array U6. The inverting input of comparator U3 is grounded, and the non-inverting input is connected to a square wave signal input. The output of comparator U3 is connected to current switch U5. The output of comparator U3 serves as the input of current switch U5, controlling the output of operational amplifier U2 or U4 to connect to resistor array U6, and outputting the waveform of the corresponding closed-loop gain signal amplitude.

2. The circuit structure with adjustable closed-loop gain signal amplitude according to claim 1, characterized in that: The current switch includes bipolar transistors Q1, Q2, Q3, and Q4; The bases of the bipolar transistors Q1, Q2, Q3 and Q4 are all connected to the output of comparator U3; The emitters of bipolar transistors Q1 and Q3 are connected, and are connected to the constant current source I1 of the bandgap reference source circuit U1; the emitters of bipolar transistors Q2 and Q4 are connected, and are connected to the constant current source I2 of the bandgap reference source circuit U1. The collectors of bipolar transistors Q1 and Q2 are connected to operational amplifier U4, and the collectors of bipolar transistors Q3 and Q4 are connected to operational amplifier U2.

3. The circuit structure with adjustable closed-loop gain signal amplitude according to claim 1, characterized in that: The resistor array U6 is connected to the output terminals of operational amplifiers U2 and U4 via a single-pole four-throw switch.

4. The circuit structure with adjustable closed-loop gain signal amplitude according to claim 3, characterized in that: The resistor array U6 includes resistors R1, R3, R5 and R7 that are respectively connected to the four throws of a single-pole four-throw switch, and resistors R2, R4, R6 and R8 that are respectively connected to one end of resistors R1, R3, R5 and R7. The blade of the single-pole four-throw switch is connected to the output terminals of operational amplifiers U2 and U4; The inverting input terminals of operational amplifiers U2 and U4, the non-inverting input terminal of operational amplifier U4, are connected to the junctions of resistors R1 and R2, resistors R3 and R4, resistors R5 and R6, or resistors R7 and R8.

5. The circuit structure with adjustable closed-loop gain signal amplitude according to claim 3, characterized in that: The resistors R1, R2, R3, R4, R5, R6, R7 and R8 are all metal thin film resistors, and their resistance values ​​are 2.5K, 2.5K, 5K, 5K, 10K, 10K, 1K and 1K, respectively.

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