Patent ID: 7880500

Claim:
A circuit for converting a lower voltage logical signal to a higher voltage logical signal, the circuit comprising: two current mirror structures each comprising a first branch and a second branch, each branch comprising at least a first transistor of a first kind, an input transistor of a second kind, and a second transistor of the first kind coupled between the respective first transistor and input transistor; wherein in each of the current mirror structures: the first transistor of the first branch and the first transistor of the second branch are arranged as a current mirror so as to mirror the current in the first branch in the second branch; the input transistor of each branch is arranged to be driven using a logical signal at the lower voltage, so as to control the current mirror structure to output a corresponding logical signal at the higher voltage; the second transistor of each branch is arranged to be driven by a fixed intermediate reference voltage so as to reduce the operating voltage of the input transistor; and the first kind is tolerant of a higher operating voltage than the second kind; and wherein the current mirror structures are coupled together by a pair of cross coupled transistors connected in parallel with the current mirrors.