Abstract
Abstract In the thesis, we designed different kinds of mixers for 5.2GHz and simulated with 0.18μm CMOS technology. There are three parts in this research, including (1)voltage switching mixer design with Dynamic Threshold Voltage MOSFET, DTMOS; (2)improvement of conversion gain and linearity for Gilbert cell mixer; (3)single stage active mixer for low supply voltage. First, we introduce DTMOS applied to voltage switching mixer. The forward body-to-source voltage of DTMOS could enhance the current gain and lower threshold voltage when it turns on. Hence lower LO power can achieve good switching. We allocated the IF frequency to 1.2GHz and set LO power to 0 dBm. Traditional NMOS and DTNMOS of switching mixers have been compared. Both have conversion loss of -3.4 dB but DTMOS switching mixer has better IIP3 (9.47 dBm) then the traditional one. Second, conversion gain and linearity of Gilbert cell mixer are trade-off for each other so the design should come to a compromise. The linearity of Gilbert cell mixer is improved with inductive degeneration and the conversion gain is increased by using inter-stage matching design. For 1.8 V supply voltage, it’s difficult to design stack structure circuit. Headroom of voltage is compressed and signal swing is limited. It will degrade the performance of mixer, so a single stage active mixer was proposed. The major specifications simulated includes, conversion gain 5.97 dB, IIP3 4.04 dBm and noise figure 9.0 dB.