BROAD-BAND 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 mu m gate length GaAs FETs and a Ge-APD with a sensitive area of 30 mu m diam. 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.