High-Performance and Low-Noise Trantenna Sub-THz Imager With Low-Impedance Analog Buffers and Reset Switch

We demonstrate a high-performance and low-noise single-chip sub-terahertz (THz) imager array by integrating ground (gnd)-out trantenna (transistor-antenna) with a reset switch, analog buffer, multiplexer, and preamplifier using 65-nm CMOS technology. The channel charge asymmetry of sub-THz pixel device is enhanced with ac-gnd and ac-open load impedance design for gnd-out and gnd-in trantenna, respectively. The reset modulation switch suppresses output overshoot. Thus, the detector delay time of gnd-out trantenna, with a considerably smaller output junction capacitance than gnd-in trantenna, is reduced to sub-
$\mu $
s regime. In 0.1-THz direct illumination setup, the gnd-out trantenna with analog buffer circuitry experimentally achieves high-speed sub-THz imager operation up to 600 kHz with a commercial-level delay time
$= {0.98}~\mu $
s (15 times faster than gnd-in case). Owing to low-impedance analog buffer design for gnd-out trantenna with high-speed reset switch modulation (
${\sim }{300}$
kHz), a high responsivity (
${R}_{V} = {620}$
kV/W) and ultralow noise-equivalent power (NEP
$= {8.44}$
pW/Hz0.5) are obtained for the peripheral circuitry-integrated sub-THz imager.