A G/sub m/-C baseband filter with automatic frequency tuning for a direct conversion IEEE802.11a wireless LAN receiver

A 5/sup th/ order GM-C baseband filter, with on-chip automatic frequency tuning, implemented in a 0.25 /spl mu/m BiCMOS process, is presented. Targeted for the channel selecting section of a direct-conversion IEEE 802.11a wireless LAN (WLAN) receiver, this filter has a 9.2 MHz passband with less than 0.3 dB passband ripple. The stop band attenuation is some 40 dB and 70 dB at 20 MHz and 40 MHz, respectively. By using highly linear low noise G/sub m/-C integrators, the filter achieves 79 /spl mu/V/sub rms/ total passband noise, 5.6 dBV passband input IP3, and 73 dB dynamic range for 1% THD with a 1 MHz input signal, while consuming less than 15 mW DC power from a 3 V supply.