A Distortionless Absolute Value Circuit Composed of Ordinary Operational Amplifiers

Abstract

The invention provides an undistorted absolute value circuit comprising common operational amplifiers. The circuit comprises the operational amplifiers U1A and U1B and a PNP type triode Q1 and is characterized in that an input signal IN is connected with the in-phase input end of U1A, the inverted-phase input end of U1A is grounded, and output of U1A is connected with a base electrode of the triode Q1; a resistor R2 is connected in series between the in-phase input ends of U1B and U1A, a resistor R3 is connected in series between the inverted-phase input end of U1B and the in-phase input end of U1A, a resistor R4 is connected between the inverted-phase input end and the output end of U1B, and a collector of the triode Q1 is connected with the in-phase input end of U1B. According to the absolute value operational circuit, when the input signal IN is larger than zero, the output end and the input end IN of U1B are equipotential, that is, OUT=IN; when the input signal IN is smaller than zero, Q1 is in saturation conduction, so that the in-phase input end of U1B is in 0 potential, that is, OUT=-IN, absolute value operation of the input signal is realized finally, the circuit is simple and reasonable in structure and low in manufacturing cost, and the output absolute value waveform is undistorted.

Description

technical field [0001] The present invention relates to an absolute value circuit, and more specifically relates to a distortion-free absolute value circuit composed of common operational amplifiers. Background technique [0002] The absolute value circuit realizes the absolute value operation of the signal, and is a widely used signal processing circuit. In the existing absolute value calculation circuit, due to the use of diodes, the waveform of the original function actually obtained is distorted, which easily leads to large errors when precise calculation is required. like figure 1 As shown, the waveform diagram of the original function to be calculated is given, figure 2 Among them, the waveform labeled 2 is the ideal waveform diagram of the absolute value of the original function, and the waveform labeled 3 is the actual waveform diagram obtained by the original function through the absolute value circuit with diodes. It can be seen that there is a large difference ...

AI Technical Summary

Problems solved by technology

In the existing absolute value calculation circuit, due to the use of diodes, the waveform of the original function actually obtained is distorted, and it is easy to cause large errors when precise calculations are required.

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