20 Gbit/s ultra-compact optical receiver front-end with variable gain transimpedance amplifier in 80 nm CMOS

An optical receiver (RX) front-end design is presented consisting of a variable-gain (VG) transimpedance amplifier (TIA), limiting amplifier, offset-compensation circuit and buffer. The measured maximum transimpedance-gain is 74 dBΩ with 9.3 GHz bandwidth. The power consumption is 13.8 mW excluding the buffer with 12.8 mW. Electrical, large-signal measurements show an error-free transmission at 20 Gbit/s with 10^-12 bit-error-rate. Electro-optical measurements of the RX are performed with test-setup on a PCB with a photo-diode. Detection up to 19 Gbit/s was possible error-free. The VG-property is demonstrated. As active peaking methods are used extensively the active-area is only 0.008 mm². The proposed design is one of the most compact and energy-efficiency optical RX for 20 Gbit/s suitable for photonic switch networks.