This paper describes the design consideration and simulation performance for a fully integrated CMOS RF front-end for 5.25GHz application. The single chip frontend circuit consists: a 2.65dB insertion loss transmit/receive switch (T/R switch), a 13dB power gain, 2.9dB NF low noise amplifier (LNA), and a 15dBm P/sub out-1dB/ power amplifier (PA). The IC has fabricated in a TSMC 0.25-/spl mu/m CMOS technology. To achieve single chip design target, this chip was designed without any off-chip matching component. The front-end circuit was designed for two operation modes: transmission mode (TX) and receiving mode (RX). We can switch two operation modes by changing the control voltage of the T/R switch. The simulation results of the TX mode has the power gain 7.27dB and the P/sub out-1dB/ is 12dBm. The RX mode power gain is 9.64dB and the IIP3 is 1.1dBm.