Variable-Phase-Shift Based High Data Rate Sub-THz FSK Transmitter Design: Theory and Implementation

Targeting the new generation of high data rate communication systems at sub-terahertz (THz), a fully integrated, energy and area efficient, 196 GHz frequency-shift keying (FSK) transmitter was designed and prototyped in a 55-nm SiGe process. By analyzing the transient dynamics of a loop of coupled oscillators, a new direct modulation technique for frequency modulation is presented. It is shown that an instantaneous frequency shift can be realized in theory as long as the coupling mode of the coupled oscillators loop system does not change. By controlling the phase shift in a system of tunable couplers, a 10 Gb/s single channel data rate wireless link was demonstrated, which is the first FSK wireless transmitter at sub-THz frequencies, and is
$5\times $
higher compared with all other previously published CMOS/BiCMOS wireless FSK transmitters. The achieved single channel data rate and energy efficiency per bit are comparable to other recently published sub-THz transmitters with more complicated modulation schemes like M-ary amplitude-shift keying (ASK), phase-shift keying (PSK), or quadratic-amplitude modulation (QAM).