Analysis and Design of a Foam-Cladded PMF Link With Phase Tuning in 28-nm CMOS

This paper presents a fully packaged 140-GHz dielectric waveguide (DWG) communication link using a foam-cladded fiber. A novel frequency shift keying (FSK) demodulator topology is proposed with a low-frequency feedback loop for optimal FSK demodulation under process, voltage, and temperature variation. The introduction of phase shifters and an on-chip local oscillator relaxes the design requirements and the IF-stage benefits from larger gain. The transmitter is based on a fundamental oscillator at 140 GHz with a transformer-coupled buffer to decrease capacitive loading. Both chips are implemented in a 28-nm bulk CMOS design with a nominal supply of 0.9 V and a combined power consumption of 230 mW. An analysis of the DWG data capacity limitations is presented and compared with measurement results. Data rates of 12 Gb/s/10 Gb/s/7 Gb/s over 1 m/2 m/4 m of touchable polytetrafluoroethylene (PTFE) fiber are achieved.