Voltage level shifting circuit

摘要

A level shifter shifts the level of an input signal from a second voltage domain to a first voltage domain. To accommodate different input signal levels (e.g., including sub-threshold input signal levels) that may arise due to changes in the supply voltage for the second voltage domain, current for a latch circuit of the level shifter is limited based on the supply voltage for the second voltage domain. In this way, a drive circuit of the level shifter that controls the latch circuit based on the input signal is able to initiate a change of state of the latch circuit over a wide range of input signal levels.

主权项

1. A method of level shifting between a first voltage domain and a second voltage domain, comprising:
receiving a supply voltage for the second voltage domain at a first circuit of a current limiting circuit, wherein the received supply voltage is not a data signal or a clock signal; limiting current sourced to a latch circuit by generating from the received supply voltage at the first circuit a signal that controls current flow through a second circuit of the current limiting circuit that is coupled in series between the latch circuit and a supply voltage for the first voltage domain; receiving an input signal from the second voltage domain; and controlling an output signal of the latch circuit based on the input signal, wherein the output signal is provided for the first voltage domain.