Amplitude Offset Estimation by Phase Comparison in Suppression Loops

In this paper, a new architecture for an RF amplitude comparator circuit is introduced. The technique employs a trigonometric relationship enacted by passive RF components to map the amplitude ratio between two co-spectral RF signals into a phase difference. The theory of operation of the circuit is discussed in detail and the results of a practical investigation are presented, validating the approach. The results demonstrate an accuracy advantage over commercially available products. Over the frequency range of 1600-2100 MHz, amplitude offset measurements to within 0.08 dB of that of a calibrated vector signal analyzer are shown.