A low-power continuous-time low-pass analog filter for IEEE 802.11 a/b/g/n wireless LANs

A low-power continuous-time low-pass analog filter suitable for IEEE 802.11 a/b/g/n wireless LANs with direct-conversion scheme is designed. The filter topology is based on Gm-C biquads. For the filter to become low-power, inverter-based transconductors with suitable common-mode feedback and feed forward circuitries are used. The output resistance of each OTA is increased by a negative parallel resistance at the output nodes. In order to compensate the process variation effects, one of the newest automatic tuning method called bulk-tuning is employed. With a 1.3-V supply voltage, this filter consumes 600 μW per biquad and the IIP3 of 10.2 dBm, 9.3 dBm and 9.0 dBm is achieved for IEEE 802.11 (a,g)/b/n direct conversion modes respectively with flat pass-band frequency response and near -40dB/dec stop-band gain reduction slope (per biquad).