Analysis of Imperfections on Performance of 4-Phase Passive-Mixer-Based High-Q Bandpass Filters in SAW-Less Receivers

It has been shown that an arrangement of four MOS switches and four baseband lowpass impedances can synthesize on-chip high-Q bandpass filters if the switches are driven by proper clock phases. The technique has been successfully utilized in receivers to replace external SAW filters. This paper analyzes performance of these filters in SAW-less receivers against imperfections such as clock phase-noise, thermal noise of switches, second-order non-linearity of switches and clock phase error. Such receivers deal with out-of-band blockers by utilizing on-chip high-Q 4-phase bandpass filters.