Patent ID: 6960956

Claim:
An apparatus for monitoring a power amplifier coupled to a transmission medium, the apparatus comprising: a detector circuit, coupled to the transmission medium, that generates first and second detector signals corresponding to fundamental and harmonic components, respectively, of a power amplifier output signal produced by the power amplifier, wherein the detector circuit comprises: a directional coupler that couples the power amplifier to the antenna and that generates an output signal responsive to the power amplifier output signal; a first power detector, coupled to the directional coupler, that generates the first detector signal from the output signal generated by the directional coupler; a capacitor shunt circuit, coupled to the transmission medium; a filter, capacitively coupled to the transmission medium by the capacitor shunt circuit, that filters the power amplifier output signal to produce a filtered output signal; a second power detector, coupled to the filter, that generates the second detector signal from the filtered output signal; and a comparing circuit, coupled to the detector circuit, that compares the first and second detector signals.