A simple method to tune the output pole of a passive mixer is proposed which leads to up to 33 dB improvement in an IEEE 802.15.4 standard compatible receiver’s IF section IIP3. This method is used in the design of an ultra-low power receiver front-end which consumes just 2.2 mW from a 1-V supply while achieving a SSB NF of approximately 9 dB. The energy-aware architecture allows for a 70 % reduction in the nominal power consumption (down to 0.7 mW) under strong signal conditions while improving the receiver’s IIP3 and not affecting the receiver’s input matching. The receiver is designed in a 0.18-μm RFCMOS technology.