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Design of a novel RF front-end structure for 2450-MHz band IEEE 802.15.4 ZigBee standard in a 0.18-mum CMOS process is presented. Utilizing a common-gate structure instead of conventional inductive degenerated common source amplifier, low noise figure is achieved with LNA bias current as low as 1mA. An analytical method is presented to minimize the noise figure of proposed common-gate LNA structure. Together with the LNA, an active Gilbert cell mixer is adopted to convert the RF signal to 2MHz IF signal. Employing an enhanced current re-use structure, simulation results show a conversion gain of 37.7dB, a Noise figure of 5.9dB and an IIP3 of -4dBm for the front-end. The RF front-end dissipates only 2.2mA from 1.8V supply.