Evaluation of capacitor ratios in automated accurate common-centroid capacitor arrays

Abstract

In this paper, design and measurement results of a test chip that intends to evaluate differences between layout techniques for rectangular unit-capacitor arrays are introduced. Precision capacitor ratios are compared using a switched-capacitor biquad and a pseudo-floating gate configuration. The test chip is used to evaluate the effectiveness of an automatic common-centroid capacitor array generation tool with arbitrary capacitor ratios. Results indicate significant improvements in ratio accuracy, which have a direct impact on a wide range of applications such as filters for wireless communications, hard drives, and high precision baseband processing.