Approaches to low-power implementations of DSP systems

Reduction of power consumption is significantly important for all high-performance digital VLSI systems. This paper reviews several approaches for low-power implementations of building blocks for digital subscriber line (DSL) systems. Low-power implementations of Reed-Solomon (RS) coders, fast Fourier transforms (FFTs), FIR filters, and equalizers, and reduction of power consumption by use of dual supply voltages are addressed. It is shown that use of separate Galois Field functional units for multiply-accumulate and degree reduction can reduce the energy consumption of RS coders dramatically. A hybrid feedforward and feedback commutator scheme-based FFT is shown to require less area and full hardware utilization efficiency. Reduction of switching activity at one or both inputs of the multipliers is a key to reduction of power consumption in FIR filters and equalizers. The switching activity can be reduced by use of transpose structure and by time-multiplexing of an unfolded filter. A well established retiming approach can be generalized to find those noncritical gates which can be operated with lower supply voltages to reduce the overall system power consumption.