Millimeter-wave Radiometer IC and Module for Passive Imaging

W-band direct-detection radiometer module and chip utilizing low-loss waveguide packaging for millimeter-wave passive imaging are presented. The total power radiometer consists of a high gain low noise amplifier (LNA) and a high-responsivity detector. The proposed module is based on a direct-detection front-end architecture employing LNAs, power detector, and baseband circuitry including the video amplifier, power supply circuit, which are contained in a waveguide-coupled metallic housing with a low insertion-loss E-plane probe based waveguide-to-microstrip transition. The measurement results of the module demonstrate that the E-plane probe structure can achieve less than 0.4 dB insertion loss and 11.8 dB return loss over the frequency range of 75-100 GHz, and show a responsivity of 8.5-43 MV/W without the video amplifier according to simulation. And the size of the designed radiometer module is 112.7×33×19 mm
³
. The radiometer chip is fabricated in a 0.13 μm SiGe BiCMOS technology, a size as small as 1.7×1.2 mm
²
is resulted. Utilizing 4 cascode amplifying stage, the radiometer chip measurement results demonstrate a gain of 35-45 dB, a responsivity of 27.2 kV/W, a noise equivalent power of around 2.5 pW/√Hz at 91 GHz with a power consumption as low as 16 mW.