Exploiting MOS Parametric Amplification to Suppress Noise in Switched-Capacitor RF Receivers

This article presents a technique to suppress noise in switched-capacitor (SC) radio frequency (RF) receivers (RXs). In the proposed technique, the sampling capacitor of a typical SC-RX is realized using a MOS capacitor. Furthermore, the same sampling MOS capacitor is switched between the inversion and depletion regions to act as a discrete-time parametric amplifier for downconverted signals. Due to the voltage gain at the front end, the noise of successive stages in the receiver chain is suppressed. Analytical expressions for the conversion gain, input impedance, and noise figure (NF) of the gain-boosted SC receiver are derived and verified through simulations. A prototype SC receiver is implemented in a CMOS 180-nm technology. In measurements, the receiver achieved 41-dB conversion gain and 3.1-dB NF over the tuning range of 0.2-to-0.95 GHz. The reduction in NF due to the parametric gain boost is >10 dB.