A robust Cartesian feedback loop for a 802.11a/b/g CMOS transmitter

An integrated circuit (IC) in 0.18 μm CMOS is presented which implements a complete wireless LAN transceiver for the IEEE 802.11a/b/g standards. We focus on the fully integrated transmitter using a wide band Cartesian feedback loop topology. The constraints usually associated with Cartesian feedback are solved using a novel mixed-signal implementation without the need for any factory calibration. At 54 Mbit/s, this transmitter achieves 3% EVM at -2 dBm output power from 4.85 GHz up to 5.7 GHz drawing 130 mA from a 1.8 V power supply. At 2.4 GHz, -2 dBm with 3% EVM is reached with 102 mA. Although not optimized for 802.11b, the circuit outputs 3 dBm with 10.5% EVM using 162 mA.