Recursive receiver down-converters with multiband feedback and gain-reuse for low-power applications
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Power minimization in wireless transceivers has become increasingly critical in recent years with the emergence of standards for short-distance applications in the 900 MHz and 2.4 GHz industrial, scientific and medical (ISM) radio bands. The demand for long battery life and better portability in such applications has led to extensive research on low power radio architectures. This dissertation introduces receiver topologies for low-power systems and presents a theoretical performance analysis of the topologies. Two fully integrated receiver down-converters that demonstrate the concept are implemented in a 0.13-[mu]m CMOS technology. These topologies employ merged mixers and IF amplifiers in order to reduce power dissipation for a given dynamic range performance. In the described topologies, the input stage of a mixer is used to simultaneously provide conversion gain and baseband amplification. This is achieved by applying the down-converted IF signal to input of the mixer. Consequently, the effective conversion gain of the design is greatly enhanced with current requirement primarily determined by the input transconductor. Potential degradation mechanisms related to instability and second-order distortion are identified and solved by the use of appropriate circuit techniques. Noise and linearity performance of the down-converters is analyzed and compared to that of conventional cascaded design counterparts. The potential for enhancement of IIP3 performance through cancellation of nonlinear products is discussed. Potential extensions of the above work including feedback-based architectures that exploit multiple loops for further maximizing the power efficiency of receiver front-ends are also presented.