VARIABLE GAIN TRANSIMPEDANCE AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide a variable gain transimpedance amplifier with a wide bandwidth and a wide linear operation region.SOLUTION: A transimpedance amplifier includes: a base grounded transistor Q1 whose emitter is connected to a signal input terminal, and whose collector is connected to a signal output terminal; a constant current source IS1 whose one end is connected to the emitter of the transistor Q1 and the other end is connected to a negative side of a power supply voltage; load resistors RL1 and RL2 connected in series between a positive side of the power supply voltage and the collector of the transistor Q1; and a variable current source IS2, whose one end is connected to a junction point of the load resistors RL1 and RL2 and the other end is connected to the emitter of the transistor Q1, capable of controlling amount of current according to a variable gain control voltage Vctl.