Patent ID: 8219044

Claim:
A direct up conversion transmitter chain, comprising: a baseband processor that generates a baseband signal; a direct up-converter that combines the baseband signal with a radio frequency (RF) carrier signal to generate an RF output signal; an antenna that transmits the RF output signal; an impairment detection and compensation feedback circuit that down-converts the RF output signal to generate an intermediate frequency (IF) signal, measures at least one signal impairment in the IF signal, and pre-distorts the baseband signal to compensate for the measured signal impairment; a band gap voltage reference that generates a reference voltage as a function of both an ambient temperature in the vicinity of the impairment detection and compensation feedback circuit and a battery supply voltage; wherein the direct up conversion transmitter chain estimates actual values for the ambient temperature and the battery supply voltage and adjusts the signal impairment by a function of the estimated ambient temperature and the estimated battery supply voltage.