A 73 GHz, 180 Ohm PHEMT transimpedance amplifier, employing gm tapering, for OC768 optical receivers

A distributed TIA with 180 Ohm transimpedance, 73 GHz 3 dB BW, group delay below 20 pS, 840 mVpp output swings, output return loss better than 15 dB through 40 GHz and a linear range above 3 mA input detector current is presented. The amplifier employs a gm tapering technique that improves transimpedance without a significant increase in power consumption. Optical-electrical performance is presented demonstrating performance suitable for both RZ and NRZ 40 GB/s systems.