Patent ID: 6987954
Filing Date: 2006-01-17
Classification: H03C,H04B

Abstract:
1. A direct up conversion transmitter chain, comprising: a baseband processor that generates an in-phase (I) baseband signal and a quadrature-phase (Q) baseband signal; an impairment compensator coupled to the I and Q baseband signals and a feedback signal that pre-distorts the I and Q baseband signals as a function of at least one signal impairment parameter in the feedback signal and generates modified I and Q baseband signals; a direct up-converter coupled to the impairment compensator that combines the modified I and Q baseband signals with a radio frequency (RF) carrier signal to generate an RF output signal; an antenna coupled to the direct up-converter that transmits the RF output signal; an impairment detector coupled to the RF output signal that down-converts the RF output signal to generate an intermediate frequency (IF) signal, estimates the signal impairment parameter from the IF signal, and generates the feedback signal, the impairment detector including temperature and voltage sensitive components; a temperature sensor that generates a temperature sensor voltage as a function of both an ambient temperature in the vicinity of the impairment detector and a battery supply voltage; a processor coupled to the IF signal and the temperature sensor voltage that estimates the signal impairment parameter from the IF signal and adjusts the signal impairment parameter by a function of the temperature sensor voltage; and a band gap voltage reference that generates a reference voltage as a function of both the ambient temperature in the vicinity of the impairment detector and the battery supply voltage, wherein the reference voltage is coupled to the processor; wherein the processor 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.