A SiGe Terahertz Heterodyne Imaging Transmitter With 3.3 mW Radiated Power and Fully-Integrated Phase-Locked Loop

Abstract

A high-power 320 GHz transmitter using 130 nm SiGe BiCMOS technology ( 220/280 GHz) is re- ported. This transmitter consists of a 4 × 4 array of radiators based on coupled harmonic oscill ators. By incorporating a signal filter structure called retu rn-path gap coupler into a differential self-feeding oscillator, the pro posed 320 GHz radiator simulta- neously maximizes the fundamental oscillation power, harmonic generation, as well as o n-chip radiation. To facilitate the TX-RX synchronization of a future tera hertz (THz) heterodyne imaging chipset, a fully-integrated phase-locked loop (PLL) is also imple- mented in the transmi tter. Such on-chip phase-locking capability is the first demonstration for all THz radiators in silicon. In the far-field measurement, the total radiated power and EIRP of the chip is 3.3 mW and 22 .5 dBm, respectively. The transmitter con- sumes 610 mW DC power, which leads to a DC-to-THz radiation efficiency of 0.54%. To the authors' best knowledge, this work presents the hi ghest radiated power and DC-to-THz radiation efficiency in silicon-based THz radiating sources.