Design and optimization of a 2.4 GHz RF front-end with an on-chip balun

A 2.4 GHz low-power,low-noise and highly linear receiver front-end with a low noise amplifier (LNA)and balun optimization is presented.Direct conversion architecture is employed for this front-end.The on-chip balun is designed for single-to-differential conversion between the LNA and the down-conversion mixer,and is optimized for the best noise performance of the front-end.The circuit is implemented with 0.35μm SiGe BiCMOS technology.The front-end has three gain steps for maximization of the input dynamic range.The overall maximum gain is about 36 dB.The double-sideband noise figure is 3.8 dB in high gain mode and the input referred third-order intercept point is 12.5 dBm in low gain mode.The down-conversion mixer has a tunable parallel R-C load at the output and an emitter follower is used as the output stage for testing purposes.The total front-end dissipation is 33 mW under a 2.85 V supply and occupies a 0.66 mm2 die size.