Broadband GaAs FET optical front-end circuit up to 5.6 GHz

Design and performance of transimpedance preamplifiers for multi-gigabit/s optical repeaters are reported using 0.3 ¿m gate length GaAs FETs and a Ge-APD with a sensitive area of 30 ¿m diameter. Through reduction of parasitic inductance and stray capacitance in chip assembly, a 3 dB down bandwidth of 8.2 GHz is achieved without a Ge-APD. A 3 dB down bandwidth of 5.6 GHz and good pulse response to 6.5 Gbit/s RZ pattern optical signals are achieved in an optical front-end circuit with a Ge-APD.