Differential diode-based variable impedance modules

A transimpedance amplifier comprising:

• a first input switch comprising a first emitter terminal, a first base terminal coupled to a first input terminal of the transimpedance amplifier, and a first collector terminal coupled to a first output terminal of the transimpedance amplifier;
• a second input switch comprising a second emitter terminal, a second base terminal coupled to a second input terminal of the transimpedance amplifier, and a second collector terminal coupled to a second output terminal of the transimpedance amplifier;
• and
• a variable impedance module coupled to the first collector and the second collector terminals, the variable impedance module comprising a differential diode switch configured to provide analog control of a gain of the transimpedance amplifier at high frequencies by varying impedance between the first collector and the second collector terminals,
• wherein the differential diode switch comprises at least four diodes arranged in a bridge including a first pair of series-connected diodes connected in parallel to a second pair of series-connected diodes, a plurality of capacitors connected to the bridge, and a current source configured to bias the diodes in the bridge to provide the analog control.