Circuits and methods for output impedance matching in switched mode circuits

摘要

An output stage 300 includes a first output switch 201 having a current path for driving an output from a first voltage rail and a second output switch 202 having a current path for selectively driving the output from a second voltage rail. A first reference switch 301 is scaled with respects to first output switch 201 and has a current path coupled to the first voltage rail. A second reference switch 302 scaled with respects to second output switch 202 has a current path coupled to a current path of first reference switch 301 at a node and the second voltage rail. The logic measures an impedance mismatch between first and second reference switches 301, 302 and proportionally varies the impedance of a selected one of first and second output switches 201, 202 in response.