Wideband Terahertz Frequency Meter and Power Meter in CMOS

This article presents a method for designing a compact wideband on-chip terahertz frequency meter and a power meter. The core of this method lies in leveraging two highly correlated terahertz incoherent detectors to create a frequency-dependent and power-independent output ratio, which allows for the precise extraction of frequency information and effectively cancels out common external interference factors, ensuring strong robustness. At a known frequency, the terahertz power can be calculated using the precharacterized voltage responsivity (R_v) and the detector output voltage. The robustness of the method against process, voltage, and temperature variations was analyzed, confirming its strong reliability and practical applicability. The proposed method was validated using a chip containing eight nested detectors fabricated in a 65-nm CMOS process. Frequency measurements demonstrated an accuracy of 1 GHz within the range of 180–500 GHz, and power measurements showed an average deviation of 8.8% across 180–500 GHz compared to a commercial power meter.