Can SG-FET Replace FET in Sleep Mode Circuits?

The Suspended Gate Field Effect Transistor (SG-FET) appears to have the potential to replace traditional FETs in sleep mode circuits, due to its abrupt switching enabled by electromechanical instability at a certain threshold voltage and its ultra low “off” current (Ioff). This paper presents a preliminary assessment of the SG-FET potential if utilized as sleep transistor in real applications, e.g., microprocessors. We first evaluate various SG-FET instances in terms of switching delay, current capability, and leakage. Subsequently, we compare these figures with the ones offered by traditional switch transistors utilized in CMOS technologies. Our simulation results indicate that SG-FET based sleep mode circuits are potentially interesting as they clearly enable substantial leakage reductions due to their extremely low “off” currents (4 orders of magnitude lower than FET) at the expense of a 4x larger active area for the same capability to drive current.