A Wideband Variable Gain Receiving Mixer Applied To 0.4?2.7 GHz

As the core module of the receiver channel,receiving mixer plays an important role in realization of multi-mode wideband RF chip.High-performance wideband mixer not only improves the overall performance of receiver channel,but also greatly enhances the flexibility of wireless system which supports multi-mode,multi-band wideband applications.In order to ensure that the RF front-end of modern wideband receiver can provide higher linearity and wider dynamic range,a wideband variable gain receiving mixer is proposed in this paper applied to 0.4?2.7 GHz.This paper designs and optimizes an architecture of receiving mixer suitable for wideband applications by comparing various basic types of mixers.Based on the performance analysis of the current-type passive mixer,the function of multi-stage gain switching is added to improve the input dynamic range of the mixer,and harmonic rejection function is used to reduce harmonic signal interference in wideband applications.In addition,a two-stage harmonic rejection structure is adopted to improve the harmonic rejection rate of the mixer and a new circuit design scheme is proposed to realize the eight-phase local oscillation signal.Finally,the completed wideband variable gain receiving mixer could work at harmonic rejection operation mode or normal operation mode,and the chip area of the dual-mode mixer can be effectively reduced by subsequent optimization design.In this paper,TSMC 65 nm RF CMOS process is used to realize circuit and layout of wideband variable gain receiving mixer,and design is finished with simulation analysis.The simulation results show that the design can achieve gain scope of 1?30 dB with 1 dB step,the noise figure better than 6.5 dB and IIP3 better than 2 dBm at highest gain,3nd and 5th harmonic rejection rate better than 55 dB and 59 dB.