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Low-power three-dimensional (3-D) graphics rendering engine with lighting acceleration is designed and implemented for handheld multimedia terminals. The lighting unit is hardware implemented and integrated into the chip for the low-power acceleration of the 3D graphics applications. We adopt the following three steps to handle the memory bandwidth problem for rendering operations. I) We find bilinear MIPMAP is the best texture filtering algorithm for handheld systems based on our developed energy-efficiency metric. With this observation, we adopt bilinear MIPMAP for our texture filtering unit, which requires only 50% of texture memory bandwidth compared with trilinear MIPMAP filtering. II) We put the depth test operation into the earlier stage of the graphics pipeline, which eliminates texture memory accesses for invisible pixels. III) We develop a power-efficient small cache system as the interface to rendering memory. The accelerator takes 181 K gates and the performance reaches 20 Mpixels/s. A test chip is implemented with 1-poly 6-metal 0.18 μm CMOS technology. It operates at the frequency of 20 MHz with 14.7 mW power consumption.
Date of Publication: Aug. 2005