Low Complexity Architecture of NPath Mixers for Low Power Application The complexity of harmonic rejection Npath mixer based receivers is studied in this paper. A solution to improve harmonic rejection without increasing the complexity is presented and compared with conventional LNAfirst receivers. This solution is based on xcfx80delayed driving signals that enable a Npath mixer to present the same harmonic rejection than its 2Npath counterparts while reducing by 2 the frequency of operation and showing a reduced number of differential gain stages and switches. A 5path mixer is thus proposed. It allows rejecting up to the 8th harmonic with only 3 differential gain stages whereas only the 6th harmonic would be rejected with conventional topologies having the same number of amplifier stages.

A 900MHz 1.25dB NoiseFigure DifferentialOutput LNA with 12.5 dBmW FoM A 900 MHz LNA with balanced output and 12.5dBmW figureofmerit (FoM) is presented. The architecture exploits the benefits of both inductive degeneration and noise cancellation which helps in achieving the optimum noise figure (NF). The LNA has a wideband gain and input matching is achieved using an offchip inductor. Inductive degeneration and quality factor (Q) of the input matching network improves the NF of the LNA (with wideband gain) at a spot frequency. The transconductance of the coreLNA is fixed by a constantgm circuit. Simulation results show that the LNA has a minimum NF of 1.25 dB at 900 MHz, transmission gain (S 21 ) of 33 dB, S 11  of xe2x88x9219 dB at 900 MHz, IIP2 of 2 dBm, and IIP 3  of xe2x88x9215 dBm. The LNA, designed in 180 nm CMOS, consumes 4.4 mA from a 1.8 V supply and has a negligible differentialgain error of 0.138 dB, at the input matched frequency. A 2.5dB NF balanced passive mixer on top of the LNA is also implemented.