A DC-offset cancellation scheme in a 5GHz direct-conversion receiver compliant with the IEEE 802.11a wireless LAN standard is presented. An analog feedback loop is used to eliminate the DC-offset at the output of the. double-balanced mixer. The test results show that the mixer with the DC-offset cancellation circuit has a voltage conversion gain of 9.5dB at 5.15GHz, a noise figure of 13.5dB, an IIP3 of 7.6dBm, a DC-offset voltage of 1.73mV eliminating 76% of DC-offset,and a power consumption of 67mW with a 3.3V supply. The direct conversion WLAN receiver has been implemented in 0.35μm SiGe BiCMOS technology.
