choosing operation mode by the input terminal adding and subtraction circuit

Published:2011/7/27 8:21:00 Author:Fiona | Keyword: input terminal, adding, subtraction, operation mode | From:SeekIC

Circuit function This is the PSD of match using silicon photodiodes.In order to reduce the error because of receiving flux,it usually carries out the operation A + B, and thus to control the laser diode power. This circuit uses the common circuit module that can add and subtract, which has 3 inputs, but has different functions,for example, only the A and B input, it's a common additive A + B circuit; if it uses C to input and uses one between A and B,you can subtract. Circuit Work This addition and subtraction circuit is composed of the inverse OP amplifier circuit, the output voltage EO can express by the following formula: Under this formula, if assuming the resistance R1 ~ R6 are equal, you can to do the addition and subtraction operations that the magnification is 1. In the inverting amplifier, the input resistor is the input impedance, if it needs high input resistance, OP amplifier should be replaced by BI-FET type, such as the TL082, etc., and removes the resistors R7, R8.



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