Kalaiselvi Sundaram

Bio: Kalaiselvi Sundaram is an academic researcher from Dr. Mahalingam College of Engineering and Technology. The author has contributed to research in topics: Carry (arithmetic) & Adder. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

Area-efficient parallel adder with faithful approximation for image and signal processing applications

Abstract: Design of low-power and area-efficient portable complementary metal–oxide–semiconductor processors for image and signal processing applications demand reduction in transistor switching and count. Adder is the fundamental block of all arithmetic operations performed in processing units. In this study, an error-tolerant parallel adder with faithful approximation is proposed that can optimise area and accuracy. In the proposed parallel adder, for n bit input and m bit adder block, least n/2m blocks are designed with approximate logic using carry by-pass addition algorithm and most n/2m blocks are designed with exact logic using carry select addition algorithm. Least significant approximate part of the adder is designed with either exact full adder (EFA) or fault-tolerant full adder (FTFA) cells. This confines the maximum error in the proposed-EFA and proposed-FTFA designs to be not more than unit bit value with weights 2[(n/2m)−1]m and 2 n /2, respectively. Two different FTFA cells are proposed and implemented in the approximate blocks. The synthesis results of the proposed-EFA, proposed-FTFA1 and proposed-FTFA2 designs using Cadence Encounter with 90 nm ASIC technology for n = 16, m = 4 demonstrated an area saving of 22.3, 28.2 and 35%, respectively, when compared to the conventional counterpart.

Area–Energy–Error Optimized Faithful Multiplier for Digital Signal Processing

Abstract: Approximate computing is a striking approach to design area-efficient low-power datapath units for fault buoyant applications. This brief presents the design of a novel 4: 2 approximate compressor that generates no error in the carry signal. The proposed compressor is employed for partial product (PP) compression in two variants of Dadda multiplier to see its effectiveness in error-resilient image and signal processing applications. In the targeted multipliers, the approximate 4:2 compressor is used in the least n PP columns, while the exact counterpart is used in the remaining most significant columns, and hence the maximum error is precisely maintained within 2n. PP compression is performed in stages using the Wallace approach, and the final two rows of sum and carry signals are added using a ripple carry adder in the basic design. In the proposed multiplier design-2, we do not generate sum bits in the approximate part. However, the proposed error-tolerant compressor is used in appropriate columns to propagate carry to the least significant column in the exact part. Performance evaluations using Cadence Encounter with 90 nm application specific integrated circuit technology revealed that the proposed-full width (P-FW) and the proposed-truncated (P-Trun) approximate multipliers demonstrate 22.7% and 32.4% power-delay product reduction compared to the standard multiplier. Implementations of the proposed multipliers in signal and image processing applications revealed superior performance in terms of accuracy compared to prior similar approximate designs.

Design of Proficient Two Operand Adder Using Hybrid Carry Select Adder with FPGA Implementation

Abstract: In every modern ICs the adders are essential components. Adder’s performance has a terrific impact on the architecture of signal processing, controller, the module of filter, the module of data storage, etc., high-speed and area-efficient circuits are the most substantial parameters in every modern integrated circuit. Carry select adder operates at high speed, but it consumes more power due to the large area. The present approach discloses different VLSI hybrid carry select adder architectures. The hybrid technology-based Carry Select adder (CSELA) consists of two stages, namely the Hancarlson adder stage and Hybrid Stage is proposed. In this technique, all the stages (4 bits in each stage) are performed simultaneously to improve the speed and area further. The propagation delays of the proposed adder are the summation of two full adders, seven Multiplexers (4:1) and BEC(3 bit) for producing Cout. The proposed work indicates that the hybrid carry select adder operates at high a speed with a lesser area than the conventional adder. The proposed design is simulated and synthesized in Xilinx ISE 12.1 using Verilog HDL with a family of Vertex6 FPGA devices (Device No. XC6VLX75T, Package FF484, Speed -3). The synthesized report shows that the speed of the proposed adder is improved by 49.06%, 52.61%, 47.58%, 19.08%, 39.9%, 1.25%, 44.43%,19.08%, 44.07% and 71.59% compared to RCA, CBL-based CSELA, CLA, Weinberger BEC-based CSELA,D latched CSELA, Brent Kung CSELA, Brent Kung RCA-based CSELA, CSA Weinberger, Conventional CSELA and Ling CSELA, respectively.

Tolerant and low power subtractor with 4: 2 compressor and a new TG-PTL-float full adder cell

Abstract: A new 1-bit full adder (FA) cell illustrating low-power, high-speed, and a small area is presented by a combination of transmission gate (TG), pass transistor logic (PTL), and float techniques. Using the proposed cell, a 4:2 compressor is implemented and its performance is investigated under diverse circumstances of voltage, temperature, and driving. The process and corners are evaluated through the process-voltage-temperature (PVT) variations and the Monte Carlo method (MCM), respectively. The accuracy and reliability of the proposed 4:2 compressor are confirmed carefully. Utilising the proposed FA and the compressor, an efficient 8-bit subtractor is implemented for bioimage processing, in particular for difference detection of images. A new mechanism is presented to improve the detection performance of digital signal processors (DSPs) by the addition and subtraction of two images for their difference. The quality of the resulted image confirms the efficiency of the proposed circuits and the method. The high performance of the circuits makes them a promising candidate for the next generation of integrated circuits (ICs) applicable to medical image processing.

Area–Energy–Error Optimized Faithful Multiplier for Digital Signal Processing

Abstract: Approximate computing is a striking approach to design area-efficient low-power datapath units for fault buoyant applications. This brief presents the design of a novel 4: 2 approximate compressor that generates no error in the carry signal. The proposed compressor is employed for partial product (PP) compression in two variants of Dadda multiplier to see its effectiveness in error-resilient image and signal processing applications. In the targeted multipliers, the approximate 4:2 compressor is used in the least n PP columns, while the exact counterpart is used in the remaining most significant columns, and hence the maximum error is precisely maintained within 2n. PP compression is performed in stages using the Wallace approach, and the final two rows of sum and carry signals are added using a ripple carry adder in the basic design. In the proposed multiplier design-2, we do not generate sum bits in the approximate part. However, the proposed error-tolerant compressor is used in appropriate columns to propagate carry to the least significant column in the exact part. Performance evaluations using Cadence Encounter with 90 nm application specific integrated circuit technology revealed that the proposed-full width (P-FW) and the proposed-truncated (P-Trun) approximate multipliers demonstrate 22.7% and 32.4% power-delay product reduction compared to the standard multiplier. Implementations of the proposed multipliers in signal and image processing applications revealed superior performance in terms of accuracy compared to prior similar approximate designs.

Area Efficient Parallel Median Filter Using Approximate Comparator and Faithful Adder

Abstract: Approximate computing is a novel approach to design area-efficient arithmetic units for portable error resilient applications. In this work, the authors have proposed a parallel architecture for median filter targeting digital image processing. Proposed parallel median filter (PMF) uses pre-sorter and post-merge units to replace corrupted processing pixel (PP) with a median of pixels in the 3X3 processing window. Approximate compare and swap (CS) blocks that can trade off area at the expense of accuracy are proposed and used in the proposed PMF. Two variants of PMF are realised based on the implementation of approximate CS units in the pre-sorter and post-merge blocks. In PMF-design1, the authors use the exact CS unit in the pre-sorter and approximate CS unit in the post-merge block (hereafter referred to as P-EA) and in PMF-design2, they use approximate CS unit in both pre-sorter and post-merge blocks (hereafter referred to as P-AA). Functionality and accuracy efficacy of the proposed PMFs are verified with the image de-noising application. Synthesis with 90 nm application specific integrated chip technology revealed that to the least, proposed PMFs demonstrate 33.75 and 41.9% area-delay product and power-delay product reductions, respectively, compared to the standard median filter.