CMOS Plasmon Detector With Three Different Body-Biasing MOSFETs

A complementary metal–oxide–semiconductor (CMOS) plasmon detector using metal–oxide–semiconductor field–effect transistors (MOSFETs) biased at three different body voltages is proposed for high sensitivity and a wide dynamic range. The detection core consists of three differential MOSFET detectors biased at different body voltages based on the photoresponse variation depending on the body potential. The sensitivity of the proposed detector is improved through an increase in the nonlinearity owing to the uses of transistors biased by negative body voltages, and the dynamic range of the detector is widened through the parallel-connected detectors individually biased at different body voltages. A 200-GHz signal is simultaneously incident to the detection cores configured in-parallel through the integrated differential antenna, and DC voltages converted using the different photoresponsivity of the cores are current-combined at the preamplifier and amplified with a three-stage folded-cascode operational amplifier. Simulation and measurement results of the proposed detector designed using TSMC 0.25- $\mu \text{m}$ CMOS technology show that the negative body-biasing (set to 0, −0.2, and −0.4 V), in the MOSFET can improve the voltage responsivity of 2.63 times, the sensitivity by 2.9-fold compared to zero body-biasing, reaching a dynamic range of 11.1% in the CMOS plasmon detector. Raster-scanned imaging for 60- $\mu \text{m}$ thick copper tapes with a line width of 6–12 mm attached to 10-mm thick Styrofoam demonstrates that the signal-to-noise ratio of 200-GHz images can be improved from 25.5 dB to 30.6 dB when using the proposed detector with three different body-biased MOSFETs.