Patent ID: 7146141

Claim:
A direct conversion receiver with DC offset compensation comprising: an antenna receiving a RF signal with a carrier frequency; a mixture module converting the RF signal with the carrier frequency received from the antenna to a baseband signal; an AGC amplifier amplifying the baseband signal from the mixture module with a gain controlled by an automatic gain control signal; an adder subtracting a first DC offset current from the baseband signal amplified by the AGC amplifier during a first time period, and subtracting the first and a second DC offset current from the baseband signal amplified by the AGC amplifier during a second time period; a DC offset cancellation circuit converting the baseband signal from the adder to a digital signal, obtaining a DC offset value in the digital signal and converting the DC offset value to the first DC offset current; a track-and-hold circuit having a capacitor, receiving the baseband signal from the adder, holding a DC offset voltage on the capacitor and transferring the DC offset voltage to the second DC offset current; and a switching circuit coupling the DC offset cancellation circuit to receive the baseband signal from the adder and decoupling the track-and-hold circuit from receiving the baseband signal from the adder during the first time period, and decoupling the DC offset cancellation circuit from receiving the baseband signal from the adder and coupling the track-and-hold circuit to receive the baseband signal from the adder during the second time period.