Modern applications, such as video and audio processing, employ many licnear transforms and filters, such as the discrete cosine transform (DCT) and fast Fourier transform (FFT). There is a need to drastically reduce the energy consumption of these applications in order to enable their ultralow energy realization on mobile devices. It is well known that all of these applications can be implemented using multiple constant multiplication (MCM). As of now, there has been no effort to synthesize ultralow energy implementations of these systems, in particular, through the use of near-threshold computing (NTC).
In order to synthesize MCM in NTC systems, we propose techniques that include minimizing the critical path through load reduction along with the creation of deep combinational logic in order to reduce the impact of process variation. We have demonstrated the effectiveness of our new techniques on both FFT and DCT applications and show up to an order of magnitude reduction in energy for the target delay.