Low-power Sequential Circuit Design Using T Flip-flops

In the past, the major concerns of the VLSI designer were area, performance, and cost; power consumption considerations were mostly of secondary concern. In recent years, however, this trend has begun to change, and, increasingly, power consumption is being given comparable weight to area and speed in VLSI design (Rabaey and Pedram 1996). One reason is that the continuing increase in chip scale integration and the operating frequency has made power consumption a major design issue in VLSI circuits. The excessive power dissipation in integrated circuits not only discourages their use in a portable device, but also causes overheating, which degrades performance and reduces the circuit lifetime. All of these factors drive designers to devote significant resources to reduce the circuit power dissipation. Indeed, the Semiconductor Industry Association identified low-power design as a critical technological direction in 1992.