To Develop and Implement Low Power, High Speed VLSI for Processing Signals using Multirate Techniques

Multirate technique is necessary for systems with different input and output sampling rates. Recent advances in mobile computing and communication applications demand low power and high speed VLSI DSP systems [4]. This Paper presents Multirate modules used for filtering to provide signal processing in wireless communication system. Many architecture developed for the design of low complexity, bit parallel Multiple Constant Multiplications operation which dominates the complexity of DSP systems. However, major drawbacks of present approaches are either too costly or not efficient enough. On the other hand, MCM and digit-serial adder offer alternative low complexity designs, since digit-serial architecture occupy less area and are independent of the data word length [1][10]. Multiple Constant Multiplications is efficient way to reduce the number of addition and subtraction in polyphase filter implementation. This Multirate design methodology is systematic and applicable to many problems. In this paper, attention has given to the MCM & digit serial architecture with shifting and adding techniques that offers alternative low complexity in operations. This paper also focused on Multirate Signal Processing Modules using Voltage and Technology scaling. Reduction of power consumption is important for VLSI system and also it becomes one of the most critical design parameter. Transistorized Multirate module which has full custom design with different circuit topology and optimization level simulated on cadence platform. Multirate modules are used AMI 0.6 um, TSMC 0.35 um, and TSMC 0.25 um technologies for different voltage scaling. The presented methodology provides a systematic way to derive circuit technique for high speed operation at a low supply voltage. Multirate polyphase interpolator and decimator are also designed and optimized at architectural level in order to analyze the terms power consumption, area and speed. DOI: 10.17762/ijritcc2321-8169.150314

On the Implementation of Efficient Channel Filters for Wideband Receivers by Optimizing Common Subexpression Elimination Methods

No abstract availabl

A high-speed integrated circuit with applications to RSA Cryptography

Merged with duplicate record 10026.1/833 on 01.02.2017 by CS (TIS)The rapid growth in the use of computers and networks in government, commercial and private communications systems has led to an increasing need for these systems to be secure against unauthorised access and eavesdropping. To this end, modern computer security systems employ public-key ciphers, of which probably the most well known is the RSA ciphersystem, to provide both secrecy and authentication facilities. The basic RSA cryptographic operation is a modular exponentiation where the modulus and exponent are integers typically greater than 500 bits long. Therefore, to obtain reasonable encryption rates using the RSA cipher requires that it be implemented in hardware. This thesis presents the design of a high-performance VLSI device, called the WHiSpER chip, that can perform the modular exponentiations required by the RSA cryptosystem for moduli and exponents up to 506 bits long. The design has an expected throughput in excess of 64kbit/s making it attractive for use both as a general RSA processor within the security function provider of a security system, and for direct use on moderate-speed public communication networks such as ISDN. The thesis investigates the low-level techniques used for implementing high-speed arithmetic hardware in general, and reviews the methods used by designers of existing modular multiplication/exponentiation circuits with respect to circuit speed and efficiency. A new modular multiplication algorithm, MMDDAMMM, based on Montgomery arithmetic, together with an efficient multiplier architecture, are proposed that remove the speed bottleneck of previous designs. Finally, the implementation of the new algorithm and architecture within the WHiSpER chip is detailed, along with a discussion of the application of the chip to ciphering and key generation

온-디바이스 합성곱 신경망 연산 가속기를 위한 고성능 연산 유닛 설계

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 전기·정보공학부, 2020. 8. 김태환.Optimizing computing units for an on-device neural network accelerator can bring less energy and latency, more throughput, and might enable unprecedented new applications. This dissertation studies on two specific optimization opportunities of multiplyaccumulate (MAC) unit for on-device neural network accelerator stem from precision quantization methodology. Firstly, we propose an enhanced MAC processing unit structure efficiently processing mixed-precision model with majority operations with low precision. Precisely, two essential works are: (1) MAC unit structure supporting two precision modes is designed for fully utilizing its computation logic when processing lower precision data, which brings more computation efficiency for mixed-precision models whose major operations are in lower precision; (2) for a set of input CNNs, we formulate the exploration of the size of a single internal multiplier in MAC unit to derive an economical instance, in terms of computation and energy cost, of MAC unit structure across the whole network layers. Experimental results with two well-known CNN models, AlexNet and VGG-16, and two experimental precision settings showed that proposed units can reduce computational cost per multiplication by 4.68∼30.3% and save energy cost by 43.3% on average over conventional units. Secondly, we propose an acceleration technique for processing multiplication operations using stochastic computing (SC). MUX-FSM based SC, which employs a MUX controlled by an FSM to generate a bit sequence of a binary number to count up for a MAC operation, considerably reduces the hardware cost for implementing MAC operations over the traditional stochastic number generator (SNG) based SC. Nevertheless, the existing MUX-FSM based SC still does not meet the multiplication processing time required for a wide adoption of on-device neural networks in practice even though it offers a very economical hardware implementation. Also, conventional enhancements have their limitation for sub-maximal cycle reduction, parameter conversion cost, etc. This work proposes a solution to the problem of further speeding up the conventional MUX-FSM based SC. Precisely, we analyze the bit counting pattern produced by MUX-FSM and replace the counting redundancy by shift operation, resulting in reducing the length of the required bit sequence significantly, theoretically speeding up the worst-case multiplication processing time by 2X or more. Through experiments, it is shown that our enhanced SC technique is able to shorten the average processing time by 38.8% over the conventional MUX-FSM based SC.온-디바이스 인공 신경망 연산 가속기를 위한 연산 회로 최적화는 저전력, 저지연시간, 높은 처리량, 그리고 이전에 불가하였던 새로운 응용을 가능케 할 수 있다. 본 논문에서는 온-디바이스 인공 신경망 연산 가속기의 곱셈-누적합 연산기(MAC)에 대해 정밀도 양자화 기법 적용 과정에서 파생한 두 가지 특정한 최적화 문제에 대해 논의한다. 첫 번째로, 낮은 정밀도 연산이 대다수를 차지하도록 준비된 다중 정밀도가 적용된 모델을 효율적으로 처리하기 위해 개선된 MAC 연산 유닛 구조를 제안한다. 구체적으로, 다음 두 가지 기여점을 제안한다: (1) 제안한 두 가지 정밀도 모드를 지원하는 MAC 유닛 구조는 낮은 정밀도 데이터를 연산할 때 유닛의 연산 회로를 최대한 활용하도록 설계되며, 낮은 정밀도 연산 비율이 대다수를 차지하는 다중 정밀도 연산 모델에 더 높은 연산 효율을 제공한다; (2) 연산 대상 CNN 네트워크에 대해, MAC 유닛의 내부 곱셈기의 `경제적인' (비트) 크기를 탐색하기 위한 비용 함수를, 전체 네트워크 레이어를 연산 대상으로 하여 연산 비용과 에너지 비용 항으로 나타냈다. 널리 알려진 AlexNet과 VGG-16 CNN 모델에 대하여, 그리고 두 가지 실험 상 정밀도 구성에 대하여, 실험 결과 제안한 유닛이 기존 유닛 대비 단위 곱셈당 연산 비용을 4.68~30.3% 절감하였으며 에너지 비용을 43.3% 절감하였다. 두 번째로, 스토캐스틱 컴퓨팅 (SC) 기반 MAC 연산 유닛의 연산 사이클 절감을 위한 기법 및 연관된 하드웨어 유닛 구조를 제안한다. FSM으로 제어되는 MUX를 통해 입력 이진수에서 만든 비트 수열을 세어 MAC 연산을 구현하는 MUX-FSM 기반 SC는 기존 스토캐스틱 숫자 생성기 기반 SC 대비 하드웨어 비용을 상당히 줄일 수 있다. 그러나 현재 MUX-FSM 기반 SC는 효율적인 하드웨어 구현과 별개로 여전히 다수의 연산 사이클을 요구하여 온-디바이스 신경망 연산기에 적용되기 어려웠다. 또한, 기존에 제안된 대안은 제각기 절감 효과에 한계가 있거나 모델 변수 변환 비용이 있는 등 한계점이 있었다. 제안하는 방법은 기존 MUX-FSM 기반 SC의 추가 성능 향상을 위한 방법을 제시한다. MUX-FSM 기반 SC의 비트 집계 패턴을 파악하고, 중복 집계를 시프트 연산으로 교체하였다. 이로부터 필요 비트 패턴의 길이를 크게 줄이며, 곱셈 연산 중 최악의 경우의 처리 시간을 이론적으로 2배 이상 향상하는 결과를 얻었다. 실험 결과에서 제안한 개선된 SC 기법이 기존MUX-FSM 기반 SC 대비 평균 처리 시간을 38.8% 줄일 수 있었다.1 INTRODUCTION 1 1.1 Neural network accelerator and its optimizations 1 1.2 Necessity of optimizing computational block of neural network accelerator 5 1.3 Contributions of This Dissertation 7 2 MAC Design Considering Mixed Precision 9 2.1 Motivation 9 2.2 Internal Multiplier Size Determination 14 2.3 Proposed hardware structure 16 2.4 Experiments 21 2.4.1 Implementation of Reference MAC units 23 2.4.2 Area, Wirelength, Power, Energy, and Performance of MAC units for AlexNet 24 2.4.3 Area, Wirelength, Power, Energy, and Performance of MAC units for VGG-16 31 2.4.4 Power Saving by Clock Gating 35 3 Speeding up MUX-FSM based Stochastic Computing Unit Design 37 3.1 Motivations 37 3.1.1 MUX-FSM based SC and previous enhancements 42 3.2 The Proposed MUX-FSM based SC 48 3.2.1 Refined Algorithm for Stochastic Computing 48 3.3 The Supporting Hardware Architecture 55 3.3.1 Bit Counter with shift operation 55 3.3.2 Controller 57 3.3.3 Combining with preceding architectures 58 3.4 Experiments 59 3.4.1 Experiments Setup 59 3.4.2 Generating input bit selection pattern 60 3.4.3 Performance Comparison 61 3.4.4 Hardware Area and Energy Comparison 63 4 CONCLUSIONS 67 4.1 MAC Design Considering Mixed Precision 67 4.2 Speeding up MUX-FSM based Stochastic Computing Unit Design 68 Abstract (In Korean) 73Docto

Versatile Montgomery Multiplier Architectures

Several algorithms for Public Key Cryptography (PKC), such as RSA, Diffie-Hellman, and Elliptic Curve Cryptography, require modular multiplication of very large operands (sizes from 160 to 4096 bits) as their core arithmetic operation. To perform this operation reasonably fast, general purpose processors are not always the best choice. This is why specialized hardware, in the form of cryptographic co-processors, become more attractive. Based upon the analysis of recent publications on hardware design for modular multiplication, this M.S. thesis presents a new architecture that is scalable with respect to word size and pipelining depth. To our knowledge, this is the first time a word based algorithm for Montgomery\u27s method is realized using high-radix bit-parallel multipliers working with two different types of finite fields (unified architecture for GF(p) and GF(2n)). Previous approaches have relied mostly on bit serial multiplication in combination with massive pipelining, or Radix-8 multiplication with the limitation to a single type of finite field. Our approach is centered around the notion that the optimal delay in bit-parallel multipliers grows with logarithmic complexity with respect to the operand size n, O(log3/2 n), while the delay of bit serial implementations grows with linear complexity O(n). Our design has been implemented in VHDL, simulated and synthesized in 0.5μ CMOS technology. The synthesized net list has been verified in back-annotated timing simulations and analyzed in terms of performance and area consumption

Multiplierless CSD techniques for high performance FPGA implementation of digital filters.

I leverage FastCSD to develop a new, high performance iterative multiplierless structure based on a novel real-time CSD recoding, so that more zero partial products are introduced. Up to 66.7% zero partial products occur compared to 50% in the traditional modified Booth's recoding. Also, this structure reduces the non-zero partial products to a minimum. As a result, the number of arithmetic operations in the carry-save structure is reduced. Thus, an overall speed-up, as well as low-power consumption can be achieved. Furthermore, because the proposed structure involves real time CSD recoding and does not require a fixed value for the multiplier input to be known a priori, the proposed multiplier can be applied to implement digital filters with non-fixed filter coefficients, such as adaptive filters.My work is based on a dramatic new technique for converting between 2's complement and CSD number systems, and results in high-performance structures that are particularly effective for implementing adaptive systems in reconfigurable logic.My research focus is on two key ideas for improving DSP performance: (1) Develop new high performance, efficient shift-add techniques ("multiplierless") to implement the multiply-add operations without the need for a traditional multiplier structure. (2) There is a growing trend toward design prototyping and even production in FPGAs as opposed to dedicated DSP processors or ASICs; leverage this trend synergistically with the new multiplierless structures to improve performance.Implementation of digital signal processing (DSP) algorithms in hardware, such as field programmable gate arrays (FPGAs), requires a large number of multipliers. Fast, low area multiply-adds have become critical in modern commercial and military DSP applications. In many contemporary real-time DSP and multimedia applications, system performance is severely impacted by the limitations of currently available speed, energy efficiency, and area requirement of an onboard silicon multiplier.I also introduce a new multi-input Canonical Signed Digit (CSD) multiplier unit, which requires fewer shift/add/subtract operations and reduced CSD number conversion overhead compared to existing techniques. This results in reduced power consumption and area requirements in the hardware implementation of DSP algorithms. Furthermore, because all the products are produced simultaneously, the multiplication speed and thus the throughput are improved. The multi-input multiplier unit is applied to implement digital filters with non-fixed filter coefficients, such as adaptive filters. The implementation cost of these digital filters can be further reduced by limiting the wordlength of the input signal with little or no sacrifice to the filter performance, which is confirmed by my simulation results. The proposed multiplier unit can also be applied to other DSP algorithms, such as digital filter banks or matrix and vector multiplications.Finally, the tradeoff between filter order and coefficient length in the design and implementation of high-performance filters in Field Programmable Gate Arrays (FPGAs) is discussed. Non-minimum order FIR filters are designed for implementation using Canonical Signed Digit (CSD) multiplierless implementation techniques. By increasing the filter order, the length of the coefficients can be decreased without reducing the filter performance. Thus, an overall hardware savings can be achieved.Adaptive system implementations require real-time conversion of coefficients to Canonical Signed Digit (CSD) or similar representations to benefit from multiplierless techniques for implementing filters. Multiplierless approaches are used to reduce the hardware and increase the throughput. This dissertation introduces the first non-iterative hardware algorithm to convert 2's complement numbers to their CSD representations (FastCSD) using a fixed number of shift and logic operations. As a result, the power consumption and area requirements required for hardware implementation of DSP algorithms in which the coefficients are not known a priori can be greatly reduced. Because all CSD digits are produced simultaneously, the conversion speed and thus the throughput are improved when compared to overlap-and-scan techniques such as Booth's recoding

ACCELERATION OF SPARSE MATRIX MULTIPLICATION USING BIT-SERIAL ARITHMETIC

Machine Learning inference requires the multiplication of large, sparse matrices. We argue that direct spatial implementation of these fixed matrices minimizes the work per- formed in the computation, and allows for significant reduction in latency and power through constant propagation and logic minimization. Bit-serial arithmetic enables massive static matrices to be implemented. We present the structure of our bit-serial matrix multiplier, and evaluate using canonical signed digit representation to further reduce logic utilization. We have implemented these matrices on a large FPGA and provide a cost model that is simple and extensible. These FPGA implementations, on average, reduce latency by 50x up to 86x versus GPU libraries. Comparing against a recent sparse DNN accelerator, we measure a 4.1x to 47x reduction in latency depending on matrix dimension and sparsity. Throughput of the FPGA solution is also competitive for a wide range of matrix dimensions and batch sizes. Finally, we discuss ways these techniques could be deployed in ASICs, making them applicable for dynamic sparse matrix computations.M.S

HIGH-SPEED CO-PROCESSORS BASED ON REDUNDANT NUMBER SYSTEMS

There is a growing demand for high-speed arithmetic co-processors for use in applications with computationally intensive tasks. For instance, Fast Fourier Transform (FFT) co-processors are used in real-time multimedia services and financial applications use decimal co-processors to perform large amounts of decimal computations. Using redundant number systems to eliminate word-wide carry propagation within interim operations is a well-known technique to increase the speed of arithmetic hardware units. Redundant number systems are mostly useful in applications where many consecutive arithmetic operations are performed prior to the final result, making it advantageous for arithmetic co-processors. This thesis discusses the implementation of two popular arithmetic co-processors based on redundant number systems: namely, the binary FFT co-processor and the decimal arithmetic co-processor. FFT co-processors consist of several consecutive multipliers and adders over complex numbers. FFT architectures are implemented based on fixed-point and floating-point arithmetic. The main advantage of floating-point over fixed-point arithmetic is the wide dynamic range it introduces. Moreover, it avoids numerical issues such as scaling and overflow/underflow concerns at the expense of higher cost. Furthermore, floating-point implementation allows for an FFT co-processor to collaborate with general purpose processors. This offloads computationally intensive tasks from the primary processor. The first part of this thesis, which is devoted to FFT co-processors, proposes a new FFT architecture that uses a new Binary-Signed Digit (BSD) carry-limited adder, a new floating-point BSD multiplier and a new floating-point BSD three-operand adder. Finally, a new unit labeled as Fused-Dot-Product-Add (FDPA) is designed to compute AB+CD+E over floating-point BSD operands. The second part of the thesis discusses decimal arithmetic operations implemented in hardware using redundant number systems. These operations are popularly used in decimal floating-point co-processors. A new signed-digit decimal adder is proposed along with a sequential decimal multiplier that uses redundant number systems to increase the operational frequency of the multiplier. New redundant decimal division and square-root units are also proposed. The architectures proposed in this thesis were all implemented using Hardware-Description-Language (Verilog) and synthesized using Synopsys Design Compiler. The evaluation results prove the speed improvement of the new arithmetic units over previous pertinent works. Consequently, the FFT and decimal co-processors designed in this thesis work with at least 10% higher speed than that of previous works. These architectures are meant to fulfill the demand for the high-speed co-processors required in various applications such as multimedia services and financial computations