1-Gb/s 80-dBΩ fully differential CMOS transimpedance amplifier in multichip on oxide technology for optical interconnects

A 1-Gb/s differential transimpedance amplifier (TIA) is realized in a 0.25-μm standard CMOS technology, incorporating the regulated cascode input configuration. The TIA chip is then integrated with a p-i-n photodiode on an oxidized phosphorous-silicon (OPS) substrate by employing the multichip-on-oxide (MCO) technology. The MCO TIA demonstrates 80-dBΩ transimpedance gain, 670-MHz bandwidth for 1-pF photodiode capacitance, 0.54-μA average input noise current, -17-dBm sensitivity for 10^-12 bit-error rate (BER), and 27-mW power dissipation from a single 2.5-V supply. It also shows negligible switching noise effect from an embedded VCO on the OPS substrate. Furthermore, a four-channel MCO TIA array is implemented for optical interconnects, resulting in less than -40-dB crosstalk between adjacent channels.