LEVEL SHIFTER
In a multivoltage design, a level shifter is required where each signal crosses from one power domain to another. The level shifter operates a buffer with one supply voltage at the input and a different supply voltage at the output. Thus, a level shifter converts a logic signal from one voltage swing to another, with a goal of having the smallest possible delay from input to output.
The library description of a level-shifter cell must have information about the type of conversion performed (high-to-low, low-to-high, or both), the supported voltage levels, and the identities of the respective power pins that must be connected to each power supply.
Synthesis and implementation tools such as Power Compiler and IC Compiler can identify nets in the design that require adjustment between the driver and receiver, find appropriate level-shifter cells in the available libraries, insert the level shifters into the netlist, place the level shifters, and route the required logic connections and respective power supplies.
For more information on creating and using level-shifter cells, see the chapter called “Advanced Low Power Modeling” in the Library Compiler User Guide: Modeling Timing, Signal Integrity, and Power in Technology Libraries; and the Power Compiler User Guide.
