An Optimized Receiver RF Front-End

A direct conversion receiver front-end for WLAN(Wireless Local Area Network) 802.11b is presented.The noise performance and impedance matching are optimized with RF input parasitic capacitance in consideration.A new mixer architecture is proposed,which is suitable for low supply voltage application.The reception path is dc coupled and a feed-back low-pass filter is added to reduce the dc-offset and 1/f noise.The circuits are implemented in SMIC′s 0.18 μm CMOS technology.Simulation results indicate that the receiver has a noise figure of 5.2 dB and IIP3 of-14.5 dBm.Operating at 1.8 V supply voltage,the circuit consumes about 100 mW of power.