A RF receiver front-end for direct sequence code division multiple access (DS-CDMA) ultrawide band (UWB) wireless system is implemented in 0.18 mum CMOS technology. The receiver includes transmit-receive switch (T/R switch), a low noise amplifier (LNA) and a down-converting mixer. The front-end delivers an average power gain of 10 dB, and an IIP3 of -13 dBm at the wide bandwidth of 3 to 4.7 GHz. In the receive mode, the T/R switch exhibits an insertion loss of 1.45-2.3 dB, a 17-dBm power 1-dB compression point (P1dB), and a 26.2-20.1 dB isolation from 3 to 5 GHz. The wideband LNA achieves an average gain of 21 dB with plusmn2 dB flatness and a noise figure of 3.15-4.8 dB