High-accuracy RF amplitude comparator

The linearity of an RF amplifier system employing envelope feedback depends crucially on the accuracy of the RF amplitude comparator. The accuracy of the comparator described here is substantially insensitive to nonlinearities in the RF detector(s), unlike traditional comparators. This is because the two RF signal amplitudes are compared prior to, rather than subsequent to, the potentially nonlinear detection process. The circuit is also substantially insensitive to the relative phase of the two RF signals.