Soo-Ik Chae

Bio: Soo-Ik Chae is an academic researcher from Seoul National University. The author has contributed to research in topics: Very-large-scale integration & Motion estimation. The author has an hindex of 21, co-authored 121 publications receiving 1296 citations. Previous affiliations of Soo-Ik Chae include Stanford University & Chonbuk National University.

Partial bus-invert coding for power optimization of application-specific systems

Abstract: This paper presents two bus coding schemes for power optimization of application-specific systems: partial pus-invert coding and its extension to multiway partial bus-invert coding. In the first scheme, only a selected subgroup of bus lines is encoded to avoid unnecessary inversion of relatively inactive and/or uncorrelated bus lines which are not included in the subgroup. In the extended scheme, we partition a bus into multiple subbuses by clustering highly correlated bus lines and then encode each subbus independently. We describe a heuristic algorithm of partitioning a bus into subbuses for each encoding scheme. Experimental results for various examples indicate that both encoding schemes are highly efficient for application-specific systems.

A fast VLSI architecture for full-search variable block size motion estimation in MPEG-4 AVC/H.264

Abstract: We describe a fast VLSI architecture for full-search motion estimation for the blocks with 7 different sizes in MPEG-4 AVC/H.264. The proposed variable block size motion estimation (VBSME) architecture consists of a 16/spl times/16 PE array, an adder tree and comparators to find all 41 motion vectors and their minimum SADs for the blocks of 16/spl times/16, 16/spl times/8, 8/spl times/16, 8/spl times/8, 8/spl times/4, 4/spl times/8 and 4/spl times/4. It employs a 2D datapath and its control of the search area data is simple and regular. The proposed VBSME can achieve 100% PE utilization by employing a preload register and a search data buffer inside each PE and allow real-time processing of 4CIF(704/spl times/576) video with 15 fps at 100 MHz for a search range of |-32/spl sim/+31|.

Partial bus-invert coding for power optimization of system level bus

Abstract: We presen t a partial bus-in vertcoding scheme for po wer optim ization of system level bus. In the proposed sch eme, we select a su b-group of bus lines involved in b us encoding to a void unnecessary inversion of b us lines not in the sub-group thereby redu cing th e total number of bus transitions. We propose a heuristic algorithm that selects the sub-grou p of bus lines for b us encoding. Ex periments on benchmark examples in dicate that the partial bus-in vert coding reduces the tot al bus tran sitions b y 62.6% on the av erage, compared to that of the unencoded patterns.

A 16-bit carry-lookahead adder using reversible energy recovery logic for ultra-low-energy systems

Abstract: In this paper, we describe an energy-efficient carry-lookahead adder using reversible energy recovery logic (RERL), which is a new dual-rail reversible adiabatic logic. We also describe an eight-phase, clocked power generator that requires an off-chip inductor. For the energy-efficient design of reversible logic, we explain how to control the overhead of reversibility with a self-energy-recovery circuit. A test chip was implemented with a 0.8 /spl mu/m CMOS technology, which included two 16-bit carry-lookahead adders to allow fair comparison: an RERL one and a static CMOS one. Experimental results showed that the RERL adder had substantial advantages in energy consumption over the static CMOS one at low operating frequencies. We also confirmed that we could minimize the energy consumption in the RERL circuit by reducing the operating frequency until adiabatic and leakage losses were equal.

nMOS reversible energy recovery logic for ultra-low-energy applications

Abstract: We propose a new fully reversible adiabatic logic, nMOS reversible energy recovery logic (nRERL), which uses nMOS transistors only and a simpler 6-phase clocked power. Its area overhead and energy consumption are smaller, compared with the other fully adiabatic logics. We employed bootstrapped nMOS switches to simplify the nRERL circuits. With the simulation results for a full adder, we confirmed that the nRERL circuit consumed substantially less energy than the other adiabatic logic circuits at low-speed operation. We evaluated a test chip implemented with 0.8-/spl mu/m CMOS technology, which included a chain of nRERL inverters integrated with a clocked power generator. The nRERL inverter chain of 2400 stages consumed the minimum energy at V/sub dd/=3.5 V at 55 kHz, where the adiabatic and leakage losses are about equal, which is only 4.50% of the dissipated energy of its corresponding CMOS circuit at V/sub dd/=0.9 V. In conclusion, nRERL is more suitable than the other adiabatic logic circuits for the applications that do not require high performance but low energy consumption.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

An 800-MHz–6-GHz Software-Defined Wireless Receiver in 90-nm CMOS

Abstract: A software-defined radio receiver is designed from a low-power ADC perspective, exploiting programmability of windowed integration sampler and clock-programmable discrete-time analog filters. To cover the major frequency bands in use today, a wideband RF front-end, including the low-noise amplifier (LNA) and a wide tuning-range synthesizer, spanning over 800 MHz to 6 GHz is designed. The wideband LNA provides 18-20 dB of maximum gain and 3-3.5 dB of noise figure over 800 MHz to 6 GHz. A low 1/f noise and high-linearity mixer is designed which utilizes the passive mixer core properties and provides around +70 dBm IIP2 over the bandwidth of operation. The entire receiver circuits are implemented in 90-nm CMOS technology. Programmability of the receiver is tested for GSM and 802.11g standards

Graphics processing systems

Abstract: A graphics processing system includes a graphics processor and a memory for storing data to be used by and generated by the graphics processor. In a first rendering pass, the graphics processor generates an array of graphics data and stores the generated array of graphics data in the memory. The array of graphics data generated in the first rendering pass is used in a subsequent rendering pass. In the first rendering pass, the graphics processor determines one or more regions of the array of graphics data that have a particular characteristic, and generates information indicative of the one or more regions. In the subsequent rendering pass, the graphics processor uses the information indicative of the one or more regions to control the reading of the array of graphics data when it is to be used in the subsequent rendering pass.

Toward multistandard mobile terminals - fully integrated receivers requirements and architectures

Abstract: In the recent past, there has been an evolution in wireless communications toward multifunctions and multistandard mobile terminals. Reducing the number of external components to a minimum is key when the same mobile terminal has to process several different standards. Highly integrated solutions in low-cost silicon technologies are thus required. Zero-IF and low-IF receiver architectures are most suitable for a high level of integration. This paper presents a review of global system for mobile communications, universal mobile telecommunication system, Bluetooth, and wireless local area network (IEEE802.11a, b, g and HiperLAN2) standards, likely to all be present in the "universal" terminal of the future, enabling global roaming and wireless connectivity. The various standards are analyzed in order to find the optimal architecture and the building-block specifications for the receive section, with particular care to the RF front-end. State-of-the-art solutions are discussed, with emphasis on direct conversion CMOS implementations. A multistandard architecture for a fully-integrated CMOS receiver is proposed.