Noise improvement using SC filters

In this paper noise analysis of three different filter designs is performed. Voltage noise spectral density and RMS noise voltage in simply designed active RC, noise optimized active RC and switched capacitor (SC) filter design are calculated for fifth order Chebyshev low pass filter, with a cut-off frequency f
_c
=3.4kHz, and pass-band ripple α
_max
=-0.5dB. All three designs are realized as a cascade of two second order sections and one first order section. All filter analysis has been performed using MATLAB and SPICE program tools. Through the analysis it is shown that SC based filter has significantly lower noise when compared with active RC based filter.