The invention discloses a
cascode transimpedance amplifier with high
gain,
low noise and optimal bias adjustment, which includes: a main
amplifier and an auxiliary
amplifier, and also includes: a connection between the output terminal of the auxiliary
amplifier and the gate of the main amplifier In between, a bias circuit with a high-pass filter structure is added to isolate the
DC bias of the main amplifier and the auxiliary amplifier, so that both work in the best bias state; a
cascode amplifier is used to replace the
DC bias in the auxiliary amplifier Common-source stage amplifier, providing higher
gain-bandwidth product; series
inductor L at the input 1 , the series
inductor L between the common-source and common-gate devices of the
cascode amplifier 2 , the two inductances, the
photodetector capacitance at the input end and the
parasitic capacitance of the MOS tube form two π-type matching networks respectively. On the premise of ensuring that the overall bandwidth of the
transimpedance amplifier is not reduced, the present invention improves the circuit
gain and reduces
noise, and finally realizes the RGC
transimpedance amplifier with high gain and
low noise.