A 10Gb/s GaAs PHEMT High Gain Preamplifier for Optical Receivers

A high gain cascade connected preamplifier for optical receivers is developed with 0.5μm GaAs PHEMT technology from the Nanjing Electronic Devices Institute.To begin with,the transimpedance amplifier has a -3dB bandwidth of 10GHz,with a small signal gain of around 9dB.The post-stage distributed amplifier (DA) has a -3dB bandwidth of close to 20GHz,with a small signal gain of around 12dB.As a whole,the cascade preamplifier has a measured small signal gain of 213dB and a transimpedance of 55.3dBΩ in a 50Ω system.With a higher signal-to-noise ratio than that of the TIA and a markedly improved waveform distortion compared with that of the DA,the measured output eye diagram for 10Gb/s NRZ pseudorandom binary sequence is clear and symmetric.