A very low voltage 9th order linear phase baseband switched capacitor filter

A very low voltage 9th order linear phase baseband switched capacitor (SC) filter has been designed to be used as part of a cellular GSM (Global System Mobile) receiver. A Gaussian-to-6dB filter of the order of seven is chosen and a second order function is added to reduce the group delay variations around 1 /spl mu/s. The filter uses a fully differential topology to increase the dynamic range and reduce the clock feed-through noise and the distortion due to low voltage amplifier. The flicker noise is reduced by using a chopper stabilization technique in opamp design. In order to reduce the charge injection two methods of delayed clock phases and dummy switches are used. The filter is realized by cascading the biquad sections. The filter has been designed in a 0.35 /spl mu/m CMOS technology and simulated with Hspice using BSIM 3V3 model. The filter operates at 2 MHz sampling frequency and 1 MHz chopping frequency with a corner frequency of 100 kHz and 7 mW power consumption.