ANALOG ADDING AND SUBTRACTING CIRCUIT, OPTICAL RECEIVING CIRCUIT, OPTICAL TRANSMITTING CIRCUIT, AUTOMATIC GAIN CONTROL AMPLIFIER CIRCUIT, AUTOMATIC FREQUENCY CHARACTERISTIC COMPENSATION AMPLIFIER CIRCUIT, AND LIMIT AMPLIFIER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To obtain desired differential output by circuit structure suitable for building into an IC.;SOLUTION: An offset compensation part of an optical receiving circuit is constituted by an analog adding and subtracting circuit having a peak hold circuit PH1 that detects a peak value of differential opposite phase voltage VAn, a peak hold circuit PH2 that detects a peak value of differential positive phase voltage VAp, a differential voltage input/differential current output amplifier Gm1 that outputs a differential positive phase current Io1p and a differential opposite phase current Io1n according to differential input voltage VAp, VAn by making the voltage VAp positive phase input and making the voltage Van opposite phase input, a differential voltage input/differential current output amplifier Gm2 that outputs a differential positive phase current Io2p and a differential opposite phase current Io2n according to differential input voltage VAnp, VApp by making peak hold voltage VAnp positive phase input and making peak hold voltage VApp opposite phase input, a resistance R1 that flows added current of the currents Io1p and Io2p and converts them into positive phase output voltage VBp, and a resistor R2 that flows added currents of the currents Io1n and Io2n and converts them into opposite phase output voltage VBn.;COPYRIGHT: (C)2003,JPO