A 10-GHz bandwidth pseudomorphic GaAs/InGaAs/AlGaAs MODFET-based OEIC receiver

High-performance quarter-micrometer pseudomorphic modulation-doped field-effect transistors (MODFETs) and a metal-semiconductor-metal (MSM) photodetector have been used in the design of a 0.85- mu m wavelength sensitive high-speed OEIC (optoelectronic integrated circuit) lightwave receiver. The receiver circuit utilizes a transimpedance amplifier topology with all active components including a variable active feedback resistor consisting of a common-gate FET. Discrete MODFETs with -0.7-V thresholds exhibit transconductances of over 500 mS/mm and f/sub T/s of approximately 70 GHz. Receiver transimpedance gains (Z/sub T/) from 200 to 1500 Omega are obtained by varying the active feedback resistor. An amplifier 3-dB analog bandwidth of 10 GHz is measured with a maximally flat Z/sub T/ response of 300 Omega , resulting in a transimpedance-bandwidth product of 3 THz- Omega . The receiver frequency response, deduced from optical pulse measurements, confirms a 10-GHz bandwidth and indicates that the receiver is suitable for unequalized 18-Gb/s NRZ communications.