Microwave power amplifier with "envelope controlled" drain power supply

A microwave power amplifier with "envelope controlled" drain power supply is presented in this paper. The aim of this new concept is the power consumption reduction. As well known, the modern modulation systems, with a high number of constellation points, exhibit a high peak-power to average-power ratio, typically of several dB. It follows that owing to the random constellation points sequence, the output power is "low" for a long time and only for a short time the output power reaches the peak value: this fact is useful in saving power supply. In practice the DC power is delivered to the amplifier depending on the input power level. In this way a DC power saving (up to 45%) is obtained. Moreover no degradation of the transmitted spectrum has been observed in comparison with the standard operating condition.