Abstract: Circuits and methods for use in amplifying amplitude and phase modulated signals. A circuit uses a combiner with dual parallel signal amplifiers feeding it. The signal amplifiers have a low output impedance while the combiner does not provide any isolation between its inputs from the signal amplifiers. As in other Chireix architectures, the signals from the signal amplifiers are phase modulated prior to being fed to the combiner. The combiner then combines these two signals and, depending on how these two signals are combined, the resulting output of the combiner is amplitude modulated. The signal amplifiers may be Class D or Class F amplifiers to provide high efficiency amplification of the signals.

Abstract: A combiner for a diversity radio receiver wherein amplitude inversion of either received signal is performed, on a selection basis, in order to maximize the resultant output combined signal. The strength of each diversity signal is monitored as well as the strength of the combined output signal. A gain control engine combines the stronger signal with either the inverted or non-inverted weaker signal to maximize the combined output (resultant) signal strength. According to another embodiment the combiner may additionally perform an amplitude adjustment whereby the in-channel noise power is also monitored and the individual channel signal-to-noise ratios are used to adjust the amplifier gains. In this embodiment the individual channel signal-to-noise ratios plus the strength of the combined output signal are used to decide whether to invert the weaker signal before combining the received signals.