An adaptive scheme for feedthrough cancellation in switched-current techniques

An adaptive scheme for the cancellation of feedthrough errors in switched-current is presented, based on the influence of the delay between two complementary clock signals driving a switch and an adjacent dummy transistor. The scheme can also be used as a complementary CMOS switch without dummy transistors. The cancellation scheme is based on the fact that the feedthrough error is a monotone function of this delay, crossing the zero-error point at some specific delay value. Control of this value from the output of an error-integrating device can hence yield adaptive cancellation. Measurements from a 1.5-μm n-well CMOS prototype confirm the viability of the proposed technique. The application and limitations of the new cancellation method are discussed