Abstract: An amplifier system to increase the efficiency of amplification systems that employ linear modulation schemes. The amplifier system has a signal amplifier for receiving a constant amplitude input signal and producing an amplified version of the input signal. A variable impedance network presents various impedances to an output of the signal amplifier responsive to a load control signal. An envelope mapping circuit coupled to the variable impedance network produces the load control signal responsive to a desired amplitude modulation (AM) envelope. The various impedances causes the desired AM envelope to be impressed upon the amplified version of the input signal.

Abstract: A load envelope following (LEF) amplifier system to increase the efficiency of amplification systems that employ linear modulation schemes. The LEF system has a signal amplifier for receiving an input signal that has an amplitude modulation (AM) envelope. The signal amplifier produces an amplified version of the input signal. A variable impedance network is coupled to an output of the signal amplifier and substantially continuously presents various impedances to the output of the signal amplifier in response to a load control signal. An envelope mapping circuit is coupled to the variable impedance network to produce the load control signal in response to and indicative of the substantially continuously varying amplitude of the AM envelope of the input signal.

Abstract: A modulation format switch in signal communication with an amplifier, which produces a plurality of modulation format signals, and a load is described. The modulation format switch includes at least one matching network in signal communication with the amplifier and the load, where the at least one matching network capable of having a plurality of impedance values corresponding to the plurality of modulation format signals. The modulation format switch also includes a controllable element in the matching network, the controllable element capable of having more than one impedance value.

Abstract: A power amplifying circuit with load adjust for control of adjacent and alternate channel power. A power amplifier amplifies an input signal to produce an amplified signal. A variable impedance network presents different impedances to the output of the power amplifier responsive to a load control signal. A peak-to-average detector provides an indication of a peak-to-average ratio of the amplified signal. A controller coupled to the peak-to-average detector and the variable impedance network produces the load control signal responsive to the indication of the peak-to-average ratio.