The Analysis And Design Of The Mixer Based On The 180nm CMOS Technology

With the development of CMOS technology, the RF front-end circuit is more and more widely used. We appreciate to get the circuit which has smaller size, lower power consumption and better characteristics. As one critical module of the RF front-end circuit, mixer is applied for the movement of the frequency. For different systems, the requirements of the mixer's performance indicators are disparate. This paper presents an active mixer applied to the GPS receiver and an ultra–wide-band mixer applied to the UWB system. Both of the mixers are based on the 0.18 um CMOS technology.Firstly, this paper introduces four global navigation satellite systems, including the GPS system, GLONASS system, GALILEO system and COMPASS system. It presents characteristics and applications of the four systems respectively. It also makes an analysis of advantages and disadvantages of several receiver structures, including the superheterodyne receiver, the zero intermediate-frequency receiver and the low intermediate-frequency receiver. Secondly, this paper introduces basic principles, classification, optimization and performance parameters of mixers. It makes detailed analysis of the Gilbert mixer's noise, gain and linearity characteristics and designs mixers with different characteristics by optimizing the Gilert mixer. This paper designs the high-gain mixer,besides the core circuit, it also designs the biasing circuit and the layout of all circuits. In addition, this paper designs the ultra-wide-band mixer by optimizing the folding mixer. At last, it gives the simulating environment and results of the mixers. The work of this paper is:In this paper, the mixer with high gain used in the GPS receiver is under the TSMC 0.18 um CMOS technology. It improves the transconductance stage on the basis of the Gilbert mixer. This paper adopts current-bleeding structure with the complementary transconcutance, and then designs the layout of the circuit. Under the 1.8V voltage, the simulation results of the layout are: the conversion gain is 17 d B, the input third-order intercept point IIP3 is-3.6d Bm, the double sideband noise figure is 9.2d B, the core circuits power consumption of the mixer is7.16 m W, the chip area is 0.07mm*0.06mm;This paper also designs an ultra-wide-band mixer used in the ultra-wide-band system, which is under the TSMC 0.18 um CMOS technology. The circuit improves the transconductance stage on the basis of the folding mixer. It improves the linearity with the forward-feed structure as the transconductance stage and broadenes the bandwidth with the shunt-peaking structure in the output load. Under the 1.8V voltage, the simulation results of the circuit are: the conversion gain is 3.32 d B-8.56 d B, the input 1d B compression point is-4.2d Bm, the double sideband noise figure is 10.83-13.13 d B, the core circuits power consumption of the mixer is 11.5m W.The mixers designed in this paper have some deficiencies. In the complementary-transconcutance mixer, the characteristic of noise remains to be improved; In the ultra-wide-band mixer, the conversion gain is slightly small and the curve is not flat enough, the result is not ideal. The folded structure in the mixer uses the parallel LC, and the load uses the series inductor, which will lead to larger layout area.