A single external impedance element is used to perform multiple circuit compensation. A reference impedance code is first generated based on matching an internal impedance generated by transistors with an impedance of the external impedance element, and then the reference impedance code can be shifted...http://www.google.com.tw/patents/US6756810?utm_source=gb-gplus-share專利 US6756810 - Apparatus and method to provide a single reference component for multiple circuit compensation using digital impedance code shifting
