A 0.324-THz transmitter based on individual 2.65 % efficiency x16 frequency multiplier chiplets for phased-array and PMF applications

A 0.324-THz multiplier-based (x16) transmitter with an on-chip patch antenna for application in phased arrays and plastic microwave fiber links has been implemented in a 130-nm SiGe:C bipolar CMOS technology with an f T / f max of 350/450 GHz. The chiplet features integrated digitally programmable power management and biasing for post‑silicon optimization. Each radio frequency circuit block can be individually tuned by a bias current generator, and a total of three programmable voltage regulators supply the three bootstrapped doublers used from 20-to-160 GHz, the two-stage 160-GHz power amplifier and the 0.32-THz frequency doubler, respectively. After rigorous optimization, measurements reveal a single-chain dc-to-THz efficiency of 2.65 % with an output power up to 6.6 dBm at 0.324 THz. The dc power consumption was 170 mW. Operated in a 1-by-4 phased array, a maximum effective isotropic radiated power of 13.1 dBm with an output power of 2.9 dBm has been measured. Beam steering is demonstrated, revealing beam scanning over 22° in one plane. Used as a transmitter for plastic microwave fiber links, the on-chip antenna enables contactless coupling to the fiber, showing overall significantly reduced path losses compared to over-the-air links. A close-to-real-world demonstration of a PMF link with up to 3.25 Gbit/s using QPSK modulation is presented, using separate unsynchronized transmitter and receiver LO signal sources. • Highly-integrated 0.32 THz transmitter chiplet built in a SiGe:C BiCMOS technology. • The TX achieves state-of-the-art output power (6.6 dBm) and efficiency (2.65%). • The TX is also applied in phased arrays and plastic microwave fiber links. • Demonstrated a 4 × 1 phased array using 0.32 THz TX chiplets on a low cost interposer. • Demonstrated a 3.25 Gbit/s no line-of-sight PMF link using the TX chiplet.