Analysis of a MOSFET operating as an RF power detector

This paper presents the analysis of a MOSFET biased in the triode region operating as a power detector. Two modes of operation are evaluated, current mode and voltage mode. For each mode, we develop expressions relating a DC signal and the squared amplitude of a RF signal. A MOSFET compact model, valid for any inversion level, is used, permitting to predict the detector behavior with a reasonable accuracy. Optimization of the CMOS power detector is discussed remarking the trade-off between sensor's sensitivity and input impedance. The approach is validated through simulations and measurements results, which present good agreement with the theory.