A Quadrature Charge-Domain Sampling Mixer With Embedded FIR, IIR, and N-Path Filters

This paper presents the analysis and design of a quadrature charge-domain down-conversion sampling mixer with embedded finite-impulse-response (FIR), infinite-impulse-response (IIR), and 4-path bandpass filters. An in-depth investigation of the principles of periodic impulse sampling, periodic windowed sampling, and periodic N-path windowed sampling is presented and their characteristics are compared. A detailed mathematical treatment of charge-domain windowed samplers with built-in sinc, FIR and IIR filters is provided. A quadrature charge-domain sampler with embedded FIR, IIR, and 4-path band-pass filters is proposed and its performance including the effect of the non-idealities of devices is investigated. The proposed design is implemented in an IBM 130 nm 1.2 V CMOS technology. Simulation results demonstrate that the proposed design is tunable over 50-250 MHz frequency range. For an 100 MHz input, the proposed design exhibits 70 dB aliasing rejection, 60 dB stop band attenuation while consuming current of 145 μA. The performance of the proposed design is further validated using the results of on-wafer measurement of the fabricated microchip.