38.5 Gb/sRoF Based Optical Receiver for 5G Mobile Remote Radio Head Applications

A 38.5 Gb/s optical receiver has been fabricated in a 130 nm SiGe-BiCMOS technology for being employed in a Radio over Fiber transceiver for 5G remote radio head application. As a transimpedance topology, a common base amplifier is used to provide a low resistance input impedance to relax connecting a photodiode with relatively high capacitance. The transimpedance amplifier (TIA) is followed by the capacitive degeneration limiting amplifier to create a degree of freedom and relax the trade-off between the gain-bandwidth product and the linearity of the receiver. Analytical methods have been investigated to provide a low-noise and high gain design. Calibrated S-parameter measurement has been done which represents a 27-GHz 3-dB bandwidth with a differential gain of 49 dBΩ with a total power consumption of 160 mW for the entire receiver. The optical receiver has also been tested in the time domain by using a 35-GHz photodetector with a responsivity of 0.1 A/W and a capacitance of 90 fF. Eye diagram measurements have revealed that the optical receiver can provide a BER of 6.37×10
^-6
, 1.3×10
^-4
, and 1.7×10
^-3
for a data rate of 15, 25, and 35 Gb/s at an input current of 32μA respectively. The fabricated receiver occupies an area of 930 μm × 930 μm including bond pads.