This paper investigates the effect of lowering the supply and threshold voltages on the energy efficiency of CMOS circuits. Using a first-order model of the energy and delay of a CMOS circuit, we show that lowering the supply and threshold voltage is generally advantageous, especially when the transistors are velocity saturated and the nodes have a high activity factor. In fact, for modern submicron technologies, this simple analysis suggests optimal energy efficiency at supply voltages under 0.5 V. Other process and circuit parameters have almost no effect on this optimal operating point. If there is some uncertainty in the value of the threshold or supply voltage, however, the power advantage of this very low voltage operation diminishes. Therefore, unless active feedback is used to control the uncertainty, in the future the supply and threshold voltage will not decrease drastically, but rather will continue to scale down to maintain constant electric fields.

No abstract

No abstract

No abstract

No abstract

No abstract

The aim of this paper is to demonstrate the benefits of squarewave excited integrated drives as a replacement for standard single-phase motors. To overcome the adverse effects of squarewave excitation on induction motor performance the motor phase number is sufficiently increased. Although the threephase PWM drive is an industry standard in power electronic drives and offers good motor performance, it's higher switching frequency leads to higher inverter losses, making this type of drive less suitable as the basis of an integrated drive. The thermal constraints in an integrated drive require low inverter losses which can be achieved with squarewave excitation. To verify this, the PWM drive has been compared against the squarewave excited multiphase drive.

No abstract