Design considerations for wide-band p-i-n/HBT monolithictransimpedance optical receivers

A comprehensive circuit and device model was developed for the design of wideband transimpedance optical receivers using heterojunction bipolar transistors (HBTs). This model is used to determine the device and circuit design that gives the highest combination of bandwidth, sensitivity, and stability. For optoelectronic integration, it is convenient to use the collector-base junction of the HBT device structure to fabricate the p-i-n detector. A resulting transistor transit-time effect is shown to cause shunt peaking in the closed-loop response or, at worst, instability. It is shown that the photodiode stray capacitance is not a major source of sensitivity degradation in flip-chip transimpedance receivers. Optimum device structures are determined for InP- and GaAs-based HBT receivers with fine-line as well as relaxed geometries