RADIO FREQUENCY PEAK DETECTION WITH SUBTHRESHOLD BIASING

摘要

A radio-frequency peak amplitude detection circuit includes a load capacitor, a current source that charges the load capacitor and set the bias current for the field effect transistors, and a pair of field effect transistors. The gates of the field effect transistors are biased at a level below the threshold voltage of the transistors. The transistors are arranged in parallel with the capacitor and are operable to drain the capacitor at a rate determined by a differential input at the gates of the transistors. The voltage across the load capacitor is low-pass filtered and has a voltage level representative of the amplitude of the differential input signal.

主权项

1. A circuit comprising:
a load capacitor; a first and a second field effect transistor, each transistor having a channel and a gate, the gate of the first transistor being coupled to a first input node and the gate of the second transistor being coupled to a second input node, the channels of the first and second field effect transistors being arranged in parallel with the load capacitor; a first current source operative to charge the load capacitor and to set a bias current for the field effect transistors; a low-pass filter connected between the load capacitor and an output node; and a biasing circuit connected to the gates of the first and second transistors, the biasing circuit being operative to provide a biasing voltage lower than a threshold voltage of the first and second transistors.