Patent ID: 8228745

Claim:
A voltage level shifter for shifting an output signal from a first voltage level to a second voltage level and then to a further boosted second voltage level, said voltage level shifter comprising: an input for receiving an input signal; an output for outputting an output signal; a first power supply input for connecting to a first voltage source supplying said first voltage level; a second power supply input for connecting to a second voltage source supplying said second voltage level; a third power supply input for connecting to a third voltage source supplying said boosted second voltage level; a first switch responsive to a first value of said input signal to connect said output to said first power supply input and responsive to a second value of said input signal to isolate said output from said first power supply input; a second switch responsive to said second value of said input signal to connect said output to said second power supply input and responsive to said first value of said input signal to isolate said second power supply input from said output; and further switches responsive to said output signal attaining a predetermined value to connect said third power supply input to said output, said further switches forming a portion of a feedback path for supplying a signal to control said second switch by overriding said second value supplied to said second switch such that said second switch is controlled to isolate said output signal from said second power supply input in response to said output signal attaining said predetermined value, such that said voltage level shifter is responsive to a predetermined change in said input signal to isolate said first power supply input from said output and to connect said second power supply input to said output and being responsive to said output signal attaining said predetermined value to connect said third power supply input to said output and to isolate said second power supply input from said output, wherein said second switch is substantially larger than any one of said further switches.