Noise Analysis And Noise Estimation Of An RF Sampling Front-end Using An SC Decimation Filter

In this paper we present the noise analysis of an SC filter for RF sampling and downconversion. The filter implementation is made in 0.12mum CMOS and is primarily intended for WLAN in the 2.4 GHz band and with 20 MHz signal bandwidth. The fundamental noise properties of switched capacitor circuits are discussed while deriving the necessary equations needed for the filter noise calculation. The influence of amplifier noise is also discussed, and a technique to remove low-frequency noise and DC offset from the amplifiers is presented. Finally, a noise estimation of a complete RF sampling front-end is made. Our results are verified by simulations using Cadence Spectre RF simulations