A 65-mW 5-Gb/s/ch current-mode common-base transimpedance amplifier array for optical interconnects

A four-channel photoreceiver array with 20-Gb throughput has been realized in a 0.8-μm Si-SiGe heterojunction bipolar transistor technology for parallel optical interconnect applications. Each channel includes a transimpedance amplifier exploiting the current-mode common-base input configuration to achieve efficient isolation of the large input parasitic capacitance. The chip module demonstrates the -3-dB bandwidth of 4.1 GHz for 0.25-pF photodiode capacitance, the midband transimpedance gain of 3.2 kΩ, the average noise current spectral density of 7.4 pA/√Hz, and -19-dBm optical sensitivity for the bit-error rate of 10^-10. Also, the array obtains less than -20-dB crosstalk between adjacent channels. The chip dissipates 65 mW in total from ±2.5-V supply.