Structures and methods for selectively applying a well bias to only those portions of a PLD where such a bias is necessary or desirable, e.g., applying a positive well bias to transistors on critical paths within a user's design. A substrate for an integrated circuit includes a plurality of wells, each...http://www.google.com.tw/patents/US6777978?utm_source=gb-gplus-share專利 US6777978 - Structures and methods for selectively applying a well bias to portions of a programmable device
