Bluetooth Transceiver Circuit And Image Rejection Mixer Circuit Analysis And Design

In this thesis, a brief introduction for the principals and performance parameters of mixer is given, and some mixer architectures are discussed. Among these architectures. CMOS switching type active mixers are further analyzed in terms of conversion gain, noise and linearity. For the first time, an analysis of the capacitive effects on the output thermal noise of switching pair is performed in this thesis. With relatively low biasing current of switching pair or high local oscillator (LO) frequency, the output thermal noise density of the switches is proportional to the parasitic capacitance loading the switching pair common source and LO frequency, and not on the LO amplitude and the bias current. Simulations validate the proposed analysis. The physical mechanism of switches" flicker noise is explained by soft-switching mode. It gives the same result as that from theoretical calculation. By using simple model, an analytic expression about the parasitic capacitances' impact on linearity is obtained.For Bluetooth transceiver application, the performance requirements for up/down mixer are introduced in brief, high-frequency models of MOS transistor and on-chip inductor are also described. Negative feedback suitable for low voltage operation and current mirror are adopted to improve the linearity of up-conversion mixer. For down-conversion mixer, folded-cascode output stage is used to increase conversion gain and reduce output noise. Based on 0.35um CMOS process, simulations are performed with 2V supply voltage. The results show that the modification is effective. The tested results show that the linearity of input stage of up-conversion mixer meets the system requirements.For the image interference in wireless communication, some methods to realize image rejection on chip are analyzed respectively. Image-rejection circuits are designed with the modified active switching type mixer and Gm-C filter. Simulation and test results show that the image rejection ratio meets the requirement of Bluetooth Lovv-IF receiver.Finally, the research is summarized and the limitation of the thesis is presented.