A novel capacitance assignment procedure for the design of sensitivity- and noise-optimized SC-filters

A procedure for determining the capacitor values for a given integrator-based SC (switched capacitor) network with given capacitor ratios is presented. A limited capacitance area is optimally distributed among the individual circuit capacitors by minimizing the overall capacitor spread while simultaneously minimizing either sensitivity or noise. Noise in SC circuits is a function of ideal SC design parameters such as capacitor ratios and capacitance levels and of the technology-dependent parameters describing the switches and amplifiers. In the description of the noise performance, a characteristic point was found which is only a function of SC design parameters and can thus serve as a measure for the noise performance. For its description a closed-form expression that has the same form as the corresponding sensitivity measure is used. With these expressions an efficient capacitance assignment optimization procedure is derived. It is implemented in the computer-aided design and optimization program package SCSYN