Data transfers and storage are crucial cost factors in multimedia systems. Systematic methodologies are needed to obtain dramatic reductions in terms of power, area and cycle count. Upcoming multi-media processing applications will require high memory bandwidth. In this paper, we estimate that a software reference implementation of an MPEG-4 video encoder typically requires Gtransfers s to main memory for a simple profile level L2. This shows a clear need for optimization and the use of intermediate memory stages. By applying our ACROPOLIS methodology, developed mainly to relieve this data access bottleneck, we have arrived at an implementation which needs a factor 65 less background accesses. In addition, we also show that we can heavily improve on the memory transfers, without sacrificing speed (even gaining about 10% on cache misses and cycles for a DEC Alpha), by aggressive source code transformations.

In this paper, a compact low-power (LP) low-voltage (LV) metal--oxide--semiconductor-only (MOS-only) variable gain amplifier (VGA) is introduced. This amplifier based on complementary MOS (CMOS) transistors operating in strong inversion is composed of a pseudo-exponential current-to-voltage converter, analog multiplier, and output stage. The gain of the amplifier is controlled exponentially by a novel wide-range pseudoexponential current-to-voltage converter implemented with two back-to-back connected current mirrors exhibiting superb exponential characteristic. Also, a new LV/LP composite transistor is introduced to increase the input dynamic range of the multiplier. The amplifier is fabricated using a 2-m MOSIS n-well process, and its simulation and measurement results are shown in detail. I. INTRODUCTION A LTHOUGH lower supply voltage directly translates to lower power consumption in digital circuits, a similar conclusion cannot necessarily be drawn for analog circuits. Therefore...