2.5 Gb/s GaAs PIN/PHEMT monolithic integrated optical receiver front end

The front end of an 850 nm monolithic integrated optical receiver has been developed with 0.5 μm GaAs PHEMT process,which comprises a PIN photodetector and a distributed amplifier.The photodetector has a diameter and capacitance of 30 μm and 0.25 pF,respectively,as well as a dark current of less than 20 nA under the reverse bias of 10 V.The distributed amplifier has a -3dB bandwidth close to 20 GHz,with a transimpedance gain of 46 dB Ω; In the range of 50 MHz ～16 GHz,both the input and output voltage standing wave ratios are less than 2; The noise figure varies from 3.03 to 6.5 dB within the bandwidth.The monolithic integrated optical receiver front end output eye diagrams for 1 Gb/s and 2.5 Gb/s NRZ pseudorandom binary sequence (PRBS) are clear and satisfying.