Capacitance spread reduction technique for low-cost switched-capacitor filters implementation

Abstract

This paper proposes a technique to reduce capacitance spread in switched-capacitor filters. The proposed technique is based on a simple charge distribution and a partial charge transfer techniques, and is applicable to various integrator topologies. Simulation results show that the proposed technique reduces the total capacitance by 70%, which is a significant reduction of filter area. Furthermore, an integrator implemented by the proposed technique is found to be insensitive to parasitic capacitances.

Analysis of capacitance spread reduction techniques for 50‐Hz switched‐capacitor notch filters

“…The SC integrator shown in Figure 5 replaced the input network with a partial charge transfer network 9 . During phase Φ 2 , the input network capacitors ( C 1 a , C 1 b , and C 1 c ) sample the input.…”

“…This large ratio will result in a large dispersion between the values of the capacitors in the SC circuit, increasing the area and power dissipation of the filter. To decrease the dispersion between capacitors, capacitance spread reduction techniques can be used 6‐14 . Some of these techniques are described in the following section.…”