A communication device is presented that has different processors and a power amplifier. One of the processors receives a signal from a monitor and indicates that an alarm exists to a diagnostics module. The other processor uses the envelope signal of the input signal to be amplified and either the signal from the diagnostics module, the monitor or the power amplifier to adjust modulation of the power supply of the power amplifier dependent on the type of alarm. The power supply voltage or headroom is maximized or frozen at the value of the last detection cycle if a fault or impairment, respectively, of the power amplifier is detected.