A quadrature charge-domain filter with an extra in-band filtering for RF receivers

Abstract

A quadrature charge-domain filter (QCDF) is proposed. This QCDF, based on the input phases, could provide a stop-band filtering and support an in-band filtering of noise. Through the use of FIR coefficient, the alias-band rejection (ABR) and in-band suppression (IBS) could be well controlled. Measurement shows the 27.1dB ABR and 31.3dB IBS from out-of-phase signals and in-phase signals, respectively. This QCDF with 36MHz bandwidth and 7.5dBm IIP3 is fabricated on the 90nm CMOS process.