Availability of positive and negative output ideal diode circuit

Published:2011/5/10 1:11:00 Author: | Keyword: Availability of positive and negative output | From:SeekIC

Circuit function The common diode has forward voltage drop and can not do tiny signal rectifier, and when the signal amplitude is large, if the ambient temperature increases, the rectifier voltage will change with it,it is difficult to form high-precision circuit. Ideal diode circuit can get zero diode characteristic.This circuit can be realized by the feedback circuit of OP amplifier. Circuit work OP amplifier A1 is the negative output's ideal diode circuit, cascades diode D1 with the output and starts to feedback from the positive of D1.In terms of the positive input signal , A1 only plays the role of a simple inverting amplifier. When negatively inputs, OP amplifys the output of A1 to be positive, D1 is disconnected.In order to ensure the circuit works in the open-loop state and to prevent saturation, it also cascades diode D2 with the output. The positive output of A1 is clamped by diode forward voltage drop. OP Amplifier A2 is a inverting amplifier that the magnification is 1,whose function is to reverse the output of A1. If using a unipolar output, the A2 removes. Circuit R3, R6 's function is using the bias current IE of the OP amplifier's inputto eliminate offset voltage, if choosing the FET input OP amplifier ,it can be removes R3, R6.



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