A current-reused ultra low power, low flicker noise direct-conversion low noise amplifier (LNA)+mixer architecture is proposed. Measurements of the proposed LNA+mixer applied for 2.4 GHz Zigbee system using 0.18 mu m CMOS technology shows 21 dB voltage gain, 6 dB noise figure, and approximately 300 KHz flicker noise corner frequency while dissipating 0.9 mA from a 1.8 V supply.