| 摘要 |
<p>This invention relates to power amplifiers, such as pulsed power amplifiers, for amplifying radio frequency signals and to a method of amplifying radio frequency signals. The power amplifier in accordance with the invention is responsive to a power level control signal so as to amplify radio frequency signals to define any one of a plurality of amplifier output power envelopes. The power amplifier comprises means (110, 112, 114) for generating a predetermined time varying signal which represents a predetermined one of the plurality of amplifier output power envelopes, means (130) for modifying the time varying signal in response to the power level control signal (124) for definition of a selected output power envelope and control means (108) for controlling the amplifier output power in response to the modified time varying signal to amplify the radio frequency signal according to the selected one of said plurality of output power envelopes. The time varying signal may be a sequence of values stored in memory (114). The modifying means may be a clipper which clips the time varying signal at a value that depends on the power level control signal or a multiplier (130) that multiplies the times varying signal by a value that depends on the power level control signal or a subtractor that substracts a value from the time varying signal which depends on the power level control signal.</p> |
