Supply Modulation Techniques for High PAPR Signals
Envelope tracking is a well established technique for linearity and efficiency enhancement of power amplifiers (PAs) operating on demanding communication signals, particularly for cellular handsets. Supply modulation is a generalization of this technique where the amplifier drain and gate supply voltages are dynamically varied, not necessarily in direct accordance to the signal envelope, which allows this technique to be extended to very high signal bandwidths and highly nonlinear PAs. In this talk we will discuss how discrete, multi-level supply modulation can be used for signal bandwidths up to 250MHz, and how simultaneous gate modulation is allowing to maintain linearity. We will further present the design tradeoffs in GaN PAs when designing for supply modulation, and GaN based, discrete, high-power supply modulators capable of supplying multiple PAs of a phased array.