Patent ID: 8718188

Claim:
A power amplifier system comprising: a power amplifier configured to amplify a radio frequency (RF) signal; and an envelope tracker configured to generate a power amplifier supply voltage for the power amplifier using an envelope of the RF signal, the envelope tracker including a buck converter configured to generate a buck voltage from a battery voltage and a digital-to-analog converter (DAC) module configured to adjust a magnitude of the buck voltage based on the envelope of the RF signal to generate the power amplifier supply voltage, the DAC module including a push DAC and a pull DAC, the push DAC configured to increase the power amplifier supply voltage when the envelope of the RF signal increases and the pull DAC configured to decrease the power amplifier supply voltage when the envelope of the RF signal decreases; a digital filter configured to receive the envelope of the RF signal and the power amplifier supply voltage and to generate a filtered envelope signal by filtering the envelope of the RF signal based at least in part on the power amplifier supply voltage; a digital shaping and delay module configured to receive the filtered envelope signal and to generate a shaped envelope signal; and a thermometer decoder configured to receive the shaped envelope signal and to decode the shaped envelope signal to generate a plurality of push DAC control signals and a plurality of pull DAC control signals, the plurality of push DAC control signals and the plurality of pull DAC control signals coded in a thermometer coding.