Patent ID: 9197199
Filing Date: 2015-11-24
Classification: H03K

Abstract:
1. A level shifter for converting between voltages within a core voltage range extending from a high core voltage level to a low core voltage level and voltages within an I/O voltage range extending from a high I/O voltage level to a low I/O voltage level, the I/O voltage range being greater than the core voltage range, the level shifter comprising: a plurality of interconnected transistors implemented as core devices adapted to operate at voltages within said core voltage range; an input connection for providing at least one of said plurality of interconnected transistors with an input signal having a voltage within said core voltage range; an output connection coupled to said plurality of interconnected transistors; a first power connection for supplying voltage at the high I/O voltage level to at least two of said plurality of interconnected transistors; a second power connection for supplying voltage at the low core voltage level to at least two of said plurality of interconnected transistors; a voltage clamping element implemented as a core device and having a threshold voltage greater than or equal to the difference between the I/O voltage range and the core voltage range, the voltage clamping element coupled to prevent overstressing said plurality of interconnected transistors with voltages beyond said core voltage range, wherein said voltage clamping element and said plurality of interconnected transistors are configured to provide a high output signal to said output connection that is at the high I/O voltage level when said input signal is at the high core voltage level and a low output signal to said output connection that is approximately one said threshold voltage above the low core voltage level when said input signal is at the low core voltage level; and an enable transistor being one of said plurality of interconnected transistors and connecting the remaining transistors in said plurality with one of said first and second power connections.