TeraFET spectrometer

For decades, TeraFETs have been used as THz and sub-THz detectors competing with commercial Schottky diode-based technology. More recently, short channel TeraFETs have been explored for THz vector detection measuring both the intensity and phase of the impinging THz or sub-THz radiation. We report on using TeraFETs as spectrometers, lineof- sight detectors, and frequency-to-digital converters. These applications use a single TeraFET excited at the gate-to-source and drain-to-source inputs, current-driven TeraFETs, or traveling wave multistage TeraFET amplifiers. Feeding the phase-shifted THz signals into the gate and source terminals of multistage TeraFET amplifiers greatly improves the response of the TeraFET spectrometer and enables the implementation of the frequency-to-digital converter using TeraFETs.