| The development of CMOS RFIC design makes the fabrication of system on a chip(SOC), consisting of radio frequency (RF), intermediate frequency (IF), and baseband frequency, to be realizable. Mixer is the most important block in WLAN front-end receivers. The performance of the mixer affects the adjacent blocks and the overall receiver performance. The main purpose of proposed mixer is to demonstrate lower voltage application with higher conversion gain and linearity, based on the traditional Gilbert mixer prototype.To achieve this purpose, we modify the traditional Gilbert cell mixer in two ways. On the one side, we adopt a new low voltage structure, it is composed of resonant circuit and bypass capacitor . This structure need lower supply voltage. This low power structure may be used in some other circuits, for example, we can find it in low noise amplifier. On the other side, we modify the gm level of Gilbert cell mixer, one differential pair is replaced by three pairs. As the result, the value of gm is improved, so the conversion gain and linearity are improved too. We realize a high performance mixer in low supply voltage, it means our movable device can work longer.The new type mixer is designed with NEC 0.35um CMOS process. At the frequency, RF of 2.4GHz, LO of 2.2GHz and IF of 200MHz, the simulation result shows the conversion gain of 7.48dB,the input P-ldB compression point of-3.4dBm and IIP3 of 8.2dBm. The supply voltage of the mixer is 2.5V with noise figure of 12.4dB and the total power consumption of 11.8mW. |
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