Patent ID: 6847249

Claim:
A highest available voltage selector circuit, comprising: a first input voltage V1 and a second input voltage V2, first and second current sources which output first and second bias currents, respectively, a comparator, comprising: first and second field-effect transistors (FETs) having their sources connected to V1 and V2, respectively, and biased with said first and second bias currents, a third FET, diode-connected, connected to said first FET at a first node and to the output of said first current source at a second node such that said third FET conducts said first bias current to said first FET, and a fourth FET, diode-connected, connected to said second FET at a third node and to the output of said second current source at a fourth node such that said fourth FET conducts said second bias current to said second FET, the gates of said first and second FETs connected to said fourth and second nodes, respectively, such that said first FET is driven on regeneratively when V1>V2 and said second FET is driven on regeneratively when V2>V1, a first switch which connects V1 to a first output terminal when said first FET is driven on, and a second switch which connects V2 to said first output terminal when said second FET is driven on such that said first output terminal is at the highest of V1 and V2.