Optimized Design of N-Phase Passive Mixer-First Receivers in Wideband Operation
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Recent developments in CMOS passive mixers have demonstrated a number of new and useful capabilities, including dynamic RF port impedance control and filter up-conversion, while also allowing low noise figure and high out-of-band linearity, all of which track wide-ranging LO frequencies and tunable baseband bandwidth. However, these circuits also bring a unique set of challenges and requirements. Here we extend a previously derived LTI model for such mixers to the general N-phase case, and discuss basic limits in performance specifications including impedance matching, noise figure and linearity. We then extend this analysis to include high-frequency effects, especially as they relate to transistor properties. We show that essentially all of the key specification of such mixers can be described in terms of an impedance ratio, a characteristic cut-off frequency, the number of phases of the mixer and some process-related parameters. Finally, we discuss how these properties relate to power consumption of LO circuitry.
D. Yang, C. Andrews and A. Molnar, "Optimized Design of N-Phase Passive Mixer-First Receivers in Wideband Operation," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 62, no. 11, pp. 2759-2770, Nov. 2015, doi: 10.1109/TCSI.2015.2479035.