An integrated circuit is described for providing a power supply to a radio frequency (RF) power amplifier (PA). The integrated circuit comprises a low-frequency power supply path comprising a switching regulator and a high-frequency power supply path arranged to regulate an output voltage of a combined power supply at an output port of the integrated circuit for coupling to a load. The combined power supply is provided by the low-frequency power supply path and high-frequency power supply path. The high-frequency power supply path comprises: an amplifier comprising a voltage feedback and arranged to drive a power supply signal on the high-frequency power supply path; and a high-frequency-path supply module arranged to provide a high frequency supply to drive the amplifier, where the high-frequency-path supply module comprises a pulse-width modulator operably coupled to the high frequency supply via a filter and arranged to provide a filtered pulse-width modulated signal to the high frequency supply.