| 摘要 |
The efficiency of an RF transmitter amplifier 500 is improved by enabling a high power peaking amplifier 503 only when the amplitude envelope of the RF input signal is high. The amplitude of the digital baseband signal is calculated by a processor. When the amplitude of the modulated RF signal is predicted to rise above a threshold the peaking amplifier 503 is enabled before the high amplitude modulated RF input signal appears on the input line 507. Preferably the peaking amplifier is enabled and disabled during intervals when the input signal amplitude is low, so as to reduce intermodulation products caused by loss of linearity during switching. The attenuators 513,517,521 are adjusted when the peaking amplifier is enabled or disabled to maintain a constant gain for the amplifier 500. The attenuator 517 may be set to a high attenuation to disable the peaking amplifier 503. |
