Circuitry for portable electronic devices is provided. The circuitry may include wireless communications circuitry and storage and processing circuitry. The wireless communications circuitry may include an antenna and a radio-frequency power amplifier with an adjustable gain mode. The radio-frequency power amplifier may amplify radio-frequency signals to a given output power. The circuitry may include an adjustable power supply circuit that supplies an adjustable power supply voltage to the power amplifier circuitry. The circuitry may also include a transceiver that produce radio-frequency signals at a specified input power to the power amplifier circuitry. The storage and processing circuitry may be used in storing calibration data. The calibration data may specify adjustments to be made to the input power to the radio-frequency power amplifier, the gain mode setting of the power amplifier, and the power supply voltage for the power amplifier to optimize performance while minimizing power consumption.