Jia-Wei Chen

Segmented bus design for low-power systems

This paper proposes a bus-segmentation method that efficiently reduces the switched capacitance on the bus. The power consumed by the bus can, therefore, be substantially reduced. The basic idea of bus segmentation is to partition the bus into several bus segments separated by pass transistors. Highly communicating devices are located to adjacent bus segments, thus, most data communication can be achieved by switching a small portion of the bus segments. As a result, power consumption and critical path delay are both reduced. Experimental results obtained by simulating a delay model and a power model demonstrate that the proposed segmented bus system reduces bus power by about 60%-70% and improves critical bus delay by about 10%-30%.

A 160K Gates/4.5 KB SRAM H.264 Video Decoder for HDTV Applications

In this paper, a low-cost H.264/AVC video decoder design is presented for high definition television (HDTV) applications. Through optimization from algorithmic and architectural perspectives, the proposed design can achieve real-time H.264 video decoding on HD1080 video (1920 times 1088@30 Hz) when operating at 120 MHz with 320 mW power dissipation. Fabricated by using the TSMC one-poly six-metal 0.18 mum CMOS technology, the proposed design occupies 2.9times2.9 mm2 silicon area with the hardware complexity of 160K gates and 4.5K bytes of local memory

A 7mW-to-183mW Dynamic Quality-Scalable H.264 Video Encoder Chip

A dynamic quality-scalable H.264 video encoder is presented for power-adaptive video encoding. In 0.13mum CMOS technology, it requires 470kgates/13.3kB SRAM and consumes 7mW/183mW in encoding 30fps CIF/HD720 video. Compared to the state-of-the-art design for real-time HD720 video encoding, a 49% reduction in gate count and a 61% reduction in internal memory is achieved

An efficient 2-D DCT/IDCT core design using cyclic convolution and adder-based realization

This paper proposes an efficient two-dimensional (2-D) discrete cosine and inverse discrete cosine transform (DCT/IDCT) core design. Adopting the row-column decomposition technique for computing 2-D DCT/IDCT, we formulate the one-dimensional (1-D) DCT/IDCT into cyclic convolution by properly arranging the input sequence, optimize the multiplications based on the concept of common subexpression sharing, and carry out the multiplications through carry-save adders (CSAs). Using cyclic convolution is helpful in exploiting the word-level data sharing in computing different DCT/IDCT outputs. Adopting the common subexpression sharing is beneficial to the bit-level data sharing in computing the outputs. As compared with some existing approaches of realizing DCT/IDCT, the proposed approach can save on average 20%/spl sim/33% in the delay-area product (gate-count * time-unit) based on a 0.35-/spl mu/m CMOS technology under the data word-lengths ranging from 16/spl sim/24 b. Besides, we have also proposed an IP generator for designing the 2-D DCT/IDCT based on the proposed approach. It provides a design-automation environment with parameter configurations in designing a 2-D DCT/IDCT core that is suitable for most image and video compression applications.

Design theory and implementation for low-power segmented bus systems

The concept of bus segmentation has been proposed to minimize power consumption by reducing the switched capacitance on each bus [Chen et al. 1999]. This paper details the design theory and implementation issues of segmented bus systems. Based on a graph model and the Gomory-Hu cut-equivalent tree algorithm, a bus can be partitioned into several bus segments separated by pass transistors. Highly communicating devices are placed to adjacent bus segments, so most data communication can be achieved by switching a small portion of the bus segments. Thus, a significant amount of power consumption can be saved. It can be proved that the proposed bus partitioning method achieves an optimal solution. The concept of tree clustering is also proposed to merge bus segments for further power reduction. The design flow, which includes bus tree construction in the register-transfer level and bus segmentation cell placement and routing in the physical level, is discussed for design implementation. The technology has been applied to a μ-controller design, and simulation results by PowerMill show significant improvement in power consumption.

A Dynamic Quality-Adjustable H.264 Video Encoder for Power-Aware Video Applications

This paper proposes a dynamic quality-adjustable H.264 baseline profile (BP) video encoder that comprises 470 Kgates and 13.3 kB SRAM in a core size of 4.3 × 4.3 mm2 using TSMC 0.13 ¿m 1P8M CMOS technology. Exploiting parameterized algorithms for motion estimation and intra prediction, the proposed design can dynamically configure the encoding modes with the design trade-off between power consumption and video quality for various video encoding applications. In addition, the proposed basic unit (BU)-based rate control hardware can maintain a constant and stable bit rate for network video transmission. It achieves real-time H.264 video encoding on CIF, D1, and HD720@30 frames/s with 7 mW to 25 mW, 27 mW to 162 mW, and 122 mW to 183 mW power dissipation in different quality modes.

Low Complexity Architecture Design of H.264 Predictive Pixel Compensator for HDTV Application

In this paper, we propose a low-complexity architecture design of H.264 predictive pixel compensator (PPC) for HDTV application. In intra prediction, we propose a shared adder-based architecture style that supports all of the 17 intra prediction modes, and reduce computational complexity in the I4MB prediction mode 3~8 up to 50% computation. Besides, we have also proposed the distributed memory access to improve the HW usage. As well as, it can be used to reduce the memory size for buffering the neighboring pixels. In inter prediction, we can save about 48% of external memory bandwidth by the data reused through the hybrid block size memory access. Adopting the mixed six-tap FIR filter architecture to design luma interpolation, we can efficiently reduce the hardware cost up to 27%. The implemental result shows the hardware cost of the proposed design is about 60854 gates under a TSMC 0.18mum CMOS technology, which achieves the real-time processing requirement for HD-1080 format video@30 Hz at the working frequency of 87 MHz

An energy-aware IP core design for the variable-length DCT/IDCT targeting at MPEG4 shape-adaptive transforms

This paper proposes a flexible hardware solution and the associated energy-aware IP core design for computing the variable-length discrete cosine transform/inverse discrete cosine transform (DCT/IDCT) required in the MPEG4 shape-adaptive DCT/IDCT (SA-DCT/IDCT). The proposed IP core has been developed based on the design concept of programmable processors to provide the flexibility in dynamically configuring the hardware. To achieve good performance both in area and speed, we optimize the proposed IP core both in the algorithmic computational complexity and hardware complexity. Furthermore, the proposed IP core possesses the feature of energy-aware design flexibility. The simulation shows that the proposed design has 44% energy reduction at the price of 0.3-dB signal quality degradation for the image compression applications. The implementation results show that the proposed IP core costs about 3100 gates along with 16 words (1 word = 16 bits) of memory, which can achieve the real-time processing of the texture coding in MPEG4 SP@L3 and ACE@L2 CODEC system for the CIF format video at 30 frames/s with 4:2:0 color format.

A Condition-based Intra Prediction Algorithm for H.264/AVC

This paper proposes a condition-based algorithm for H.264/AVC 4times4 intra prediction. Exploiting high correlation existed in neighboring intra prediction modes, we propose the three conditions to skip the less possible candidates in doing intra4times4 block mode decision. When compared to the 9 prediction modes in the full search algorithm, the proposed algorithm can complete a 4times4 intra prediction using 4.4 prediction modes operation in average. The simulation result shows that the proposed algorithm can reduce computational complexity up to 44% at the cost of less than 0.1 dB PSNR loss in average

A Quality Scalable H.264/AVC Baseline Intra Encoder for High Definition Video Applicaitons

In this paper, we propose a quality scalable H.264/AVC baseline intra encoder with two hardware sharing mechanisms and three timing optimizing schemes. The proposed hardware sharing schemes share the common terms among intra prediction of different modes to reduce the hardware cost. The proposed timing optimizing schemes are used to improve the data throughput rate. The proposed design supports different clock rates of 26/33/47 MHz and 70/85 MHz to encode SD and HD720 video sequences with 30fps respectively with different qualities. According to a 0.13¿m CMOS technology, the proposed design costs 170K gates and 4.43 KB of internal SRAM at clock rate of 130MHz.