CUHK electronic theses & dissertations collection

For the first method, a novel linearization scheme for CMOS double-balanced mixer based on the use of multi-bias dual-gate transistors is presented. In this technique, two intermodulation distortion components with proper phase relationship, generated by devices operating at different bias conditions, are added together to cancel each other for the improvement of mixer's linearity. The measured performance of a fabricated CMOS mixer operating at RF frequency of 2.45GHz and LO frequency of 2.35GHz is demonstrated. Over 35dB of IMD reduction is achieved by the proposed method under optimal biasing condition.In the second design, a novel linearization scheme for cascode amplifier based upon capacitive feedback is presented. This method involves the optimal design of the feedback network for IMD reduction. By using Volterra series analysis, expression for IMD products is derived and the corresponding circuit parameters for optimized linearity are obtained. For experimental verification, CMOS cascode amplifiers are designed and fabricated to operate at 2.45GHz with supply voltage of 2V. By measurement, IIP3 is improved of almost 7dB by using the proposed feedback technique. The performance dependency of the fabricated amplifiers under different bias conditions is also examined. The results indicate that the proposed technique can offer low sensitivity to the variation of process parameters.Linearity is one of the major requirements in modern communication systems due to the limited channel spacing. In the past years, various linearization schemes have been studied extensively for RF circuit design such as low-noise amplifiers and power amplifiers. These techniques offer IMD reduction at the expense of circuit complexity. In the last decade, much effort has been devoted to the development of single-chip RF transceiver using sub-micron CMOS technology. This thesis presents three simple and effective linearization techniques for CMOS mixer and amplifier design. They are experimentally verified by circuit fabrication based on 0.35mum CMOS process.The last approach combines the advantages of source degeneration and the capacitive feedback for cascode amplifier linearization. Experiments are performed on CMOS amplifiers operating at 2.45GHz, and more than 11dB of IIP3 enhancement is observed.Au Yeung, Chung Fai."August 2007."Adviser: Chang Kwok Keung.Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1189.Thesis (Ph.D.)--Chinese University of Hong Kong, 2007.Includes bibliographical references (p. 153-161).Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Abstract in English and Chinese.School code: 1307