A Fully-integrated 110-GHz Wideband Direct-detection Imaging Unit MMIC Integrating Balanced Power Detector and Log-periodic Antenna

this paper presents a 110-GHz wideband direct-detection imaging unit integrating balanced power detector and log-periodic antenna in 0.25 μm GaAs pHEMT technology. The detector mainly consists of a 90° bridge, two identical transistors for detection, and a low-pass filter. Coplanar waveguides (CPW) are deployed to implement transmission lines in a compact size. In addition, an on-chip log-periodic antenna is co-designed to connect with the detector. Simulation results demonstrate that the peak responsivity of the detector is 8 kV/ W at 98 GHz with a 3 dB bandwidth from 85.9 GHz to 128.9 GHz and a low in-band noise equivalent power (NEP) of 0.87-1.5 pW/Hz1/2. The simulated $\boldsymbol{S}_{11}$ is less than -7.6 dB at 75–140 GHz. The overall size of the chip is 2.7 × 1 mm2including pads.