New methodologies for low-power high-performance digital VLSI design.

摘要

Historically, VLSI designers have focused on increasing the speed and reducing the area of digital systems. However, the evolution of portable systems and advanced Deep Sub-Micron (DSM) fabrication technologies, has brought power dissipation as another critical design factor. Low-power design reduces cooling cost and increases reliability especially for high-density systems. Moreover, it reduces the weight and size of portable devices. Yet, high-performance is still the main criterion for most digital systems, which may not be sacrificed to achieve lower power dissipation. This thesis presents new low-power high-performance digital VLSI design methodologies for process, circuit, and algorithm level design.; On the process level, future challenges in device scaling such as short channel effects, subthreshold leakage currents, and hot carrier effects are discussed. The influence of technology scaling on the performance, power, and area of different CMOS logic styles is then analyzed and simulated. This study covers five logic families; namely, CMOS, CPL, Domino, DCVS and CML. The scalability of each logic style and its potential in future technology generations are explored.; On the circuit level, a new logic family for low-power high-performance applications is presented. This logic family combines the speed, low supply voltage, and noise immunity of CML circuits with the low standby current and design simplicity of dynamic circuits. The new logic style reduces the power by 7% and the delay by 73% compared to conventional CMOS logic. A 16-bit CLA adder is designed, simulated, fabricated, and tested using 0.61μ m CMOS technology. Test results have confirmed the functionality of the new logic family at various supply voltages.; Also, a new Domino logic style, called High-Speed Domino (HS-Domino), has been developed. HS-Domino resolves the trade-off between noise margin and speed associated with the conventional Domino logic. Simulation results show that HS-Domino circuits are superior to conventional Domino ones in terms of power, speed, and tolerance to the leakage currents in DSM technologies.; This study also presents new Multiple Threshold CMOS (MTCMOS) scheme for dynamic circuits. This scheme is applied to Domino and DDCVS logic styles. The new implementations reduce the leakage power by orders of magnitude keeping the noise margin intact, and maintain the high performance and low dynamic power of low VT circuits. Unlike other MTCMOS Domino logic implementations, the new scheme does not require additional hardware.; At the algorithm level, a new algorithm for high radix division is presented. The algorithm uses a look-up table to estimate the quotient digit at each iteration. The look-up table is optimized to reduce power dissipation and delay of the divider. Simulation results show that the new algorithm reduces the power dissipation by 22% and 12% for radix 8 and radix 16 division, respectively, compared to other division algorithms. The algorithm also increases the speed by a factor of 13% and 10%, for radix 8 and radix 16 division, respectively.