Transimpedance optical preamplifier with a very low input resistance

A PIN photodiode-bipolar transistor transimpedance optical preamplifier with a very low input resistance is described that exhibits certain advantages over more conventional designs using common-emitter or common-collector input stages. The common-base input configuration enables optimum performance to be maintained with lower-cost photodiodes exhibiting a moderate capacitance of 2-7 pF.