Adjustable impedance circuit and impedance setting method for providing differential-mode impedance matching and common-mode impedance matching

摘要

An adjustable impedance circuit includes a calibration module, an impedance module, a first switch module and a second switch module. The calibration module is arranged to generate a calibration signal. The impedance module has a plurality of impedance elements. The first switch module is coupled to the calibration module, and is arranged to receive the calibration signal and make a first portion of the impedance elements be selectively coupled between a differential input port and at least one reference voltage according to the calibration signal. The second switch module is coupled to a common-mode voltage output node, and is arranged to receive a control signal and make a second portion of the impedance elements be selectively coupled between the common-mode voltage output node and the differential input port according to the control signal.