CN204009924U - A kind of high precision absolute value circuit - Google Patents

Abstract

The utility model relates to a high-precision absolute value circuit; the technical problem to be solved is: to provide a high-precision absolute value circuit that can accurately output the absolute value of a sine wave; the technical solution adopted is: the inverting input terminal of the operational amplifier A1 One end of the resistor R3 is connected in parallel with the cathode of the diode D1 and then connected to one end of the resistor R1, the other end of the resistor R1 is connected in parallel with one end of the resistor R2 and then connected to the voltage input terminal Vin, and the other end of the resistor R2 is connected in parallel with one end of the resistor R6, One end of the resistor R4 and one end of the resistor R5 are connected to the inverting input terminal of the operational amplifier A2, the other end of the resistor R4 is connected in parallel to the other end of the resistor R3 and then connected to the anode of the diode D2, and the cathode of the diode D2 is connected in parallel to the diode D1 The positive pole is connected to the output terminal of the operational amplifier A1, and the other end of the resistor R5 is connected to the sliding terminal of the potentiometer R7; it is suitable for absolute value circuits.

Description

A High Precision Absolute Value Circuit

technical field

The utility model relates to an absolute value circuit, in particular to a high-precision absolute value circuit.

Background technique

In the circuit system, the AC signals of various circuits have negative signal components. In the specific use process, the negative signal part needs to be changed into a positive signal first, that is, an absolute value circuit needs to be added to make the output signal the absolute value of the input signal or the same as The absolute value is proportional; in the prior art, the most commonly used absolute value circuit is to use a rectifier diode directly. This method is simple and easy, but due to the forward voltage drop of the diode, it is impossible to obtain a high-precision absolute value voltage. And due to the non-linearity of the operational amplifier, when the amplitude of the sine wave changes, there is a deviation in the output of the circuit, and the absolute value of the sine wave cannot be accurately output; in addition, most of the traditional absolute value circuits can only output the absolute value of the input signal, and cannot Outputs signals such as the effective value of the input signal, and has a narrow range of applications.

Utility model content

The utility model overcomes the deficiencies of the prior art, and the technical problem to be solved is: to provide a high-precision absolute value circuit with small circuit output deviation and capable of accurately outputting the absolute value of a sine wave.

In order to solve the above-mentioned technical problems, the technical solution adopted by the utility model is: a high-precision absolute value circuit, including an operational amplifier A1, the inverting input terminal of the operational amplifier A1 is connected in parallel with one end of the resistor R3 and the negative pole of the diode D1 One end of the resistor R1 is connected, the other end of the resistor R1 is connected in parallel with one end of the resistor R2 and then connected with the voltage input terminal Vin, and the other end of the resistor R2 is connected in parallel with one end of the resistor R6, one end of the resistor R4 and the resistor R5. One end is connected to the inverting input terminal of the operational amplifier A2, the other end of the resistor R4 is connected in parallel with the other end of the resistor R3 and connected to the positive pole of the diode D2, and the negative pole of the diode D2 is connected in parallel with the positive pole of the diode D1. The output end of the amplifier A1 is connected, the other end of the resistor R5 is connected to the sliding end of the potentiometer R7, the two ends of the potentiometer R7 are respectively connected to the +12V voltage and the -12V voltage, and the other end of the resistor R6 is connected to the The output terminal of the operational amplifier A2 is connected to the voltage output terminal Vout, and the non-inverting input terminal of the operational amplifier A1 and the non-inverting input terminal of the operational amplifier A2 are both grounded.

The absolute value circuit also includes a single-pole double-throw switch S1, a capacitor C1 and a resistor R8, the single-pole double-throw switch S1 is arranged on the line between the resistor R6 and the output terminal of the operational amplifier A2, and the single-pole double-throw The moving end of the throw switch S1 is connected to the resistor R6, the fixed end a1 of the SPDT switch S1 is connected to the output end of the operational amplifier A2, and the fixed end b1 of the SPDT switch S1 is connected in series The resistor R8 is connected to the output terminal of the operational amplifier A2, and the capacitor C1 is connected to the two ends of the resistor R8 in parallel; the resistance of the resistor R2, the resistor R6, the resistor R1, the resistor R3 and the resistor R4 is The relationship is: R2= R6=2×R1=2×R3=2×R4.

Compared with the prior art, the utility model has the following beneficial effects:

1. In the high-precision absolute value circuit in the present utility model, a voltage divider circuit composed of resistance R5 and potentiometer R7 is added to the inverting input terminal of the operational amplifier A2 in the addition circuit, and the voltage divider circuit can be used for the operational amplifier A1 Compensate with the non-linearity of the operational amplifier A2, so that the output can be adjusted by adjusting the potentiometer R7 compensation voltage when the sine wave amplitude changes, so that the output deviation of the circuit can be reduced, and the absolute value of the sine wave can be output accurately.

2. In the utility model, a SPDT switch S1 can also be set on the circuit between the output terminal of the resistor R6 and the operational amplifier A2, the moving end of the SPDT switch S1 is connected with the resistor R6, and the SPDT switch S1 The fixed terminal a1 is connected to the output terminal of the operational amplifier A2, the fixed terminal b1 of the SPDT switch S1 is connected in series with the resistor R8 and then connected to the output terminal of the operational amplifier A2, and the capacitor C1 is connected in parallel to both ends of the resistor R8; When the moving end of the double-throw switch S1 is placed at the fixed end a1, the circuit outputs the absolute value of the sine wave; when the moving end of the single-pole double-throw switch S1 is placed at the fixed end b1, the circuit outputs the effective value of the absolute value of the sine wave, This makes the circuit more practical and increases the application range of the high-precision absolute value circuit.

Description of drawings

Below in conjunction with accompanying drawing, the utility model is described in further detail;

Fig. 1 is the structural representation of the utility model.

Detailed ways

As shown in Figure 1, a high-precision absolute value circuit includes an operational amplifier A1, the inverting input terminal of the operational amplifier A1 is connected in parallel with one end of the resistor R3 and the cathode of the diode D1, and then connected with one end of the resistor R1. The other end of the resistor R1 is connected in parallel with one end of the resistor R2 and then connected to the voltage input terminal Vin, and the other end of the resistor R2 is connected in parallel with one end of the resistor R6, one end of the resistor R4, and one end of the resistor R5, and then the reverse phase of the operational amplifier A2 The input terminal is connected, the other end of the resistor R4 is connected in parallel with the other end of the resistor R3 and then connected to the anode of the diode D2, the cathode of the diode D2 is connected in parallel with the anode of the diode D1 and then connected to the output terminal of the operational amplifier A1, the said The other end of the resistor R5 is connected to the sliding end of the potentiometer R7, the two ends of the potentiometer R7 are respectively connected to the +12V voltage and the -12V voltage, and the other end of the resistor R6 is connected to the output terminal of the operational amplifier A2 in parallel with the The voltage output terminal Vout is connected, and the non-inverting input terminal of the operational amplifier A1 and the non-inverting input terminal of the operational amplifier A2 are all grounded; in this embodiment, the resistance values of the resistor R2, resistor R6, resistor R1, resistor R3 and resistor R4 The relationship can be: R2= R6=2×R1=2×R3=2×R4, when the amplitude of the input sine wave changes, by adjusting the potentiometer R7, the operational amplifier A1 and the operational amplifier A2 can be compensated to reduce The influence of the non-linearity of the operational amplifier is eliminated, and the output of the circuit is more accurate.

Specifically, the absolute value circuit may further include a single-pole double-throw switch S1, a capacitor C1 and a resistor R8, the single-pole double-throw switch S1 is arranged on the line between the resistor R6 and the output terminal of the operational amplifier A2, The moving end of the SPDT switch S1 is connected to the resistor R6, the fixed end a1 of the SPDT switch S1 is connected to the output end of the operational amplifier A2, and the fixed end of the SPDT switch S1 The terminal b1 is connected to the output terminal of the operational amplifier A2 after the resistor R8 is connected in series, and the capacitor C1 is connected in parallel to both ends of the resistor R8; the design of the single-pole double-throw switch S1 makes it convenient for the circuit to output a sine wave The absolute value and the effective value of the absolute value enhance the practicability of the circuit.

The above embodiments of the utility model have been described in detail in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned embodiments. Make various changes below.

Claims (3)

1. A high-precision absolute value circuit, characterized in that: comprise an operational amplifier A1, the inverting input terminal of the operational amplifier A1 is connected in parallel with one end of the resistance R3 and the negative pole of the diode D1 and is connected with one end of the resistance R1, the said The other end of the resistor R1 is connected in parallel with one end of the resistor R2 and then connected to the voltage input terminal Vin, and the other end of the resistor R2 is connected in parallel with one end of the resistor R6, one end of the resistor R4, and one end of the resistor R5, and then the reverse phase of the operational amplifier A2 The input terminal is connected, the other end of the resistor R4 is connected in parallel with the other end of the resistor R3 and then connected to the anode of the diode D2, the cathode of the diode D2 is connected in parallel with the anode of the diode D1 and then connected to the output terminal of the operational amplifier A1, the said The other end of the resistor R5 is connected to the sliding end of the potentiometer R7, the two ends of the potentiometer R7 are respectively connected to the +12V voltage and the -12V voltage, and the other end of the resistor R6 is connected to the output end of the operational amplifier A2 in parallel with the The voltage output terminal Vout is connected, and the non-inverting input terminal of the operational amplifier A1 and the non-inverting input terminal of the operational amplifier A2 are both grounded. 2. A high-precision absolute value circuit according to claim 1, characterized in that: the absolute value circuit also includes a single-pole double-throw switch S1, a capacitor C1 and a resistor R8, and the single-pole double-throw switch S1 is set at On the line between the resistor R6 and the output terminal of the operational amplifier A2, the movable terminal of the SPDT switch S1 is connected to the resistor R6, and the fixed terminal a1 of the SPDT switch S1 is connected to the operational amplifier A2. The output terminal of the amplifier A2 is connected, the fixed terminal b1 of the SPDT switch S1 is connected in series with the resistor R8 and then connected to the output terminal of the operational amplifier A2, and the capacitor C1 is connected in parallel to both terminals of the resistor R8 end. 3. A high-precision absolute value circuit according to claim 1 or 2, characterized in that: the resistance relationship of the resistors R2, R6, R1, R3 and R4 is: R2=R6=2 ×R1=2×R3=2×R4.