Patent ID: 7570931

Claim:
An RF transmitter configured to transmit an RF signal within a predetermined frequency band using a variably biased RF power amplifier, said RF transmitter comprising: a power source; an RF power amplifier having a power input, a signal input, and a signal output; a switching element coupled between said power source and said power input of said RF power amplifier, said switching element supplying a bias voltage to said RF power amplifier; a communication-signal source configured to supply a communication signal, said communication-signal source being coupled to said signal input of said RF power amplifier; a peak detector having an input coupled to said communication-signal source and an output; an out-of-band power estimator having an input coupled to said output of said RF power amplifier and having an output, said out-of-band power estimator being configured to estimate power occurring outside of said predetermined frequency band; and a control section having a first input coupled to said output of said peak detector, a second input coupled to said output of said out-of-band power estimator, and an output coupled to said switching element, said control section being configured to adjust said bias voltage supplied to said RF power amplifier so that said out-of-band power estimated by said out-of-band power estimator is less than or equal to a predetermined power level.