A New Analog-Based Lo Harmonic Rejection Technique With Tunable Notch Frequency

An effective technique for mixer lo harmonic rejection in a saw-less wideband receiver front-end is proposed. the proposed technique provides a tunable notch that can be placed at any frequency like mixer lo harmonics, to avoid the aliasing in baseband after mixing. an analog lc notch is used in a cascode transconductor, and it can reject one of the 3rd or 5th harmonics. this notch frequency is tunable using the bond wire inductors or fixed gyrator-c active inductor, and a capacitor array, without any significant power/area overhead on overall system. since the accurate value of inductance is not clear, a calibration circuit is proposed to tune this lc notch. this tuning phase runs in forground, and consumes very low additional power. this technique is used in a wideband receiver front-end. post-layout simulation in 130nm cmos results in an average 3rd harmonic rejection ratio of 36 db. the overall circuit consums 34mw power and a has a noise figure of 3.4db at 1ghz frequency.