A novel offset current cancellation technique for switched-current circuits and systems

Abstract

This paper presents an unique offset current cancellation technique called multiple-path feedback compensation (MPFC) which can greatly reduce offset currents at the output and internal nodes of SI circuits and systems. A 5th-order Chebyshev SI filter is used as an example for the implementation and the verification of the proposed MPFC technique. 90 test chips have been fabricated with a 1 /spl mu/m CMOS n-well digital process. Increased percentages of the chip area and the power consumption due to the use of the MPFC circuit are 5% and 4%, respectively. Measured results show that the variance of output offset currents is reduced to 2% of its original amount. Besides, the peak signal-to-noise ratio (SNR) is increased by 3 dB and the total harmonic distortion (THD) is reduced by 10 dB.