Mismatch Detection using Replica Circuit

Abstract

An apparatus for detecting an operating characteristic mismatch at an output of an amplifier by using a replica circuit is presented. In one exemplary case, a detected voltage difference at the output of the two circuits is used to drive a tuning control loop to minimize an impedance mismatch at the output of the amplifier. In another exemplary case, the replica circuit is used to detect a fault in operation in a corresponding main circuit. A method for detecting a load mismatch in a main RF circuit using the replica circuit is also presented.

What is claimed is: 
     
         1 . An arrangement for detecting and controlling impedance mismatch in a radio frequency (RF) circuit, comprising:
 a first RF circuit configured such that, during operation of the arrangement, to amplify a first input signal, thus producing a first output signal at an output port of the first RF circuit that is an amplified version of the first input signal;   a first load coupled to the output port of the first RF circuit;   a second RF circuit configured such that, during operation of the arrangement, to amplify a second input signal, thus producing a second output signal that is an amplified version of the second input signal, the second RF circuit being a reduced size replica of the first RF circuit;   a second load connected to an output terminal of the second RF circuit, configured, during operation of the arrangement, to provide a substantially matched impedance at the output terminal of the second RF circuit; and   a detector configured such that, during operation of the arrangement, to compute a difference between the first output signal and the second output signal, thus producing a difference signal, wherein the difference signal is a function of impedance mismatch between the first RF circuit and the first load.