Differential RF Power Detector with Common Mode Rejection

A power detector circuit that rejects the common mode portion of a differential signal is disclosed. The circuit includes a differential input having first and second input nodes. Differential and common mode circuit paths are coupled to the differential input. The common mode circuit path includes first and second capacitors coupled to respective first terminals of first and second input nodes of the differential input. The second terminal of each of the first and second capacitors is coupled to a gate terminal of a first bias transistor. The common mode circuit path is configured to reject a common mode portion of a differential input signal provided to the differential input such that a differential output signal is indicative of an amount of power of a differential portion of the differential input signal.