Improving the stability of the mobile radio power amplifier

The spectral purity of mobile transmitters becomes increasingly important as the radio spectrum becomes congested and as wideband operation is offered. The environment for the radio frequency power amplifier is especially harsh with variations in supply voltage, ambient temperature, output power, load impedance, drive power, and operating frequency. Various methods for improving stability such as wideband output loading, input loading, negative feedback, and hybrid isolation are reviewed.