Wireless communications circuitry in an electronic device may include power amplifier circuitry that is powered using a bias voltage supplied by adjustable power supply circuitry. The power supply circuitry may include envelope tracking circuitry that continuously adjusts the bias voltage. The wireless communications circuitry may generate test signals and may generate performance metric data from the test signals. Processing circuitry may generate bias voltage calibration data based on the performance metric data and may provide the calibration data to the envelope tracking circuitry. After the calibration data has been generated, the envelope tracking circuitry may continuously select bias voltages to provide to the amplifier based on the magnitude of signals that are transmitted and the calibration data. By actively adjusting the bias voltage in this way, power consumption may be minimized without generating undesirable harmonics or other radio-frequency performance requirement violations.