Multi-channel length is a technique for reducing power leakage in both active and idle modes on CMOS (

MOSFET The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which d ...

) technology. Other techniques to reduce leakage, like

power gating Power gating is a technique used in integrated circuit design to reduce power consumption, by shutting off the current to blocks of the circuit that are not in use. In addition to reducing stand-by or leakage power, power gating has the benefi ...

and SRAM retention, are targeted at reducing leakage power when the device, or portions of it, are not operating. Short channel length devices provide higher performance than longer channel length devices, but the longer channel length has significantly reduced

subthreshold leakage Subthreshold conduction or subthreshold leakage or subthreshold drain current is the current between the source and drain of a MOSFET when the transistor is in subthreshold region, or weak-inversion region, that is, for gate-to-source voltages b ...

current. In this generation of the power management tool box, two channel lengths summarized in the table below were used for the speed vs. leakage trade-off. Timing-critical paths are constructed of short channel length cells, but for non timing-critical paths, the longer channel length cells can be used to trade off speed for lower leakage. Multiple channel length synthesis achieves up to 30% leakage reduction. One additional usage of longer channel length transistors is for always-on logic and for special power management cells (isolation cells, always on buffers, etc.) where speed is not critical.

References

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