Gain linearity and bandwidth improvement of InP-based transimpedance amplifiers by feedback loop designs

InP-based transimpedance amplifiers with two different active feedback loop designs, i.e. a common-gate FET (CG-FET) feedback and a gate-source connected FET (GS-FET) feedback, have been fabricated, characterized, and compared with each other. Owing to a better linearity of a feedback resistance in GS-FETs, amplifiers with this feedback design exhibit a large/sup /spl Delta/Vout/ at a small input current. Furthermore, the operational bandwidth of GS-FET feedback amplifier is also improved by eliminating the associated parasitic effect.