A new twelve-transistor approximate 4:2 compressor in CNTFET technology

Power consumption is a serious concern in the field of digital design. Reducing power supply voltage, power gating, transistor downscaling, voltage over scaling, applying modern technology and approximate computing are some candidate means in reducing power consumption. Among these candidates, approximate computing can generate a trade-off between accuracy and power-delay-area efficiency in error resilient applications. According to Moore’s law together with CMOS problems in nanoscale regime, modern technologies emerge to solve these problems. Among these recent technologies, CNTFET technology is considered as promising. As multiplication is frequently applied in multimedia processing, implementing efficient multipliers constitute critical. Compressors are fundamental elements in reduction tree multipliers and improve their efficiency, thus an improvement in multipliers’ performance. A new 12-transistor approximate 4:2 compressor is proposed here. This new appropriate compressor, in terms of area, power consumption, accuracy and reliability design, is more efficient than its existing counterparts.     

Graded-channel MOSFET (GCMOSFET) for high performance, low voltageDSP applications

Graded-Channel MOS (GCMOS) VLSI technology has been developed to meet the growing demand for low power and high performance applications. In this paper, it will be shown that, compared to conventional complementary metal-oxide-semiconductor (CMOS), the GCMOS device offers the advantage of significantly higher drive current, capable of lower threshold voltage with improved punchthrough resistance, lower body effect and lower series resistance, thus making it most suitable for applications that require both high performance and low power consumption, such as digital signal processing (DSP). This is demonstrated, for the first time, by much improved low voltage circuit performance of a DSP logic circuit fabricated using a 0.5 μm GCMOS process. At 1.8 V, a 30% speed improvement over CMOS is achieved, and the power-delay product is reduced by 25%. In addition, similar speed improvement is achieved in SRAM's with consistent performance improvement over a wide range of temperatures between -50 and 150°C     

A comparative study of energy/power consumption in parallel decimal multipliers

Decimal multiplication is a frequent operation with inherent complexity in implementation. Commercial and financial applications require working with decimal numbers while it has been shown that if we convert decimal number to binary ones, this will negatively influence the preciseness required for these applications. Existing research works on parallel decimal multipliers have mainly focused on latency and area as two major factors to be improved. However, energy/power consumption is another prominent issue in today׳s digital systems. While the energy consumption of parallel decimal multipliers has not been addressed in previous works, in this paper we present a comparative study of parallel decimal multipliers, considering energy/power consumption, leakage and dynamic power consumption, beside latency and area. This study can provide some guidelines for EDA tools and hardware designers to choose proper multiplier based on given applications and design constraints. All designs in were implemented using VHDL and synthesized in Design-Compiler toolbox with TSMC 45 nm technology file.     

有效的模(2n+1)乘算法及其VLSI设计

模乘运算在剩余数值系统、数字信号处理系统及其它领域都具有广泛的应用,模乘法器的硬件实现具有重要的作用。提出了一种改进的模(2~n 1)余数乘法器的算法及其硬件结构,其输入为通常的二进制表示,因此无需另外的输人数据转换电路而可直接用于数字信号处理应用。通过利用模(2~n 1)运算的周期性简化其乘积项并重组求和项,以及采用改进的进位存储加法器和超前进位加法器优化结构以减少路径延时和硬件复杂度。比较其它同类设计,新的结构具有较好的面积、延时性能。     

Carry-save architectures for high-speed digital signal processing

Carry-save arithmetic, well known from multiplier architectures, can be used for the efficient CMOS implementation of a much wider variety of algorithms for high-speed digital signal processing than, only multiplication. Existing architectural strategies and circuit concepts for the realization of inner-product based and recursive algorithms are recalled. The two's complement overflow behavior of carry-save arithmetic is analyzed and efficient overflow correction schemes are given. Efficient approaches are presented for the carry-save, implementation of a saturation control. The concepts are extended and refined for the high-throughput implementation of decisiondirected algorithms such as division, modulo multiplication and CORDIC which have yet been avoided because of a lack of efficient concepts for implementation.It is shown, that the carry-save technique can be extended to a comprehensive method to implement high-speed DSP algorithms. Successfully fabricated commercial VLSI circuits emphasize the potential of this method.     

High Performance Significance Approximation Error Tolerance Adder for Image Processing Applications

Addition is one of the fundamental arithmetic operations which are used extensively in many VLSI systems such as microprocessors and application specific DSP architectures. In this paper, the Significance Approximation Error Tolerant Carry Select Adder (SAET-CSLA) is constructed, which is efficient in terms of accuracy, power and area. While considering the elementary structure of an image processing applications, it is a combination of the multipliers and delays, which in turn are the combination of the adders. This research paper describes the Algorithmic strength reduction technique which leads to a reduction in hardware complexity by exploiting the significances. This transformation is basically implemented for the reduction in the power consumption and area efficient of Very Large Scale Integration (VLSI) design or iteration period in a programmable Digital Signal Processing (DSP) implementation. The significance approximation error tolerant adder is designed using full adder and approximate full adder cells with reduced complexity at the gate level. The performance of 16 bit conventional Carry Select Adder (CSLA), 16 bit Error Tolerant carry select Adder (ET-CSLA) and proposed Significance Approximation Error Tolerant Carry Select Adder (SAET-CSLA) are compared. For all the 2¹⁶ input combinations, comparison is made between existing and proposed CSLA adders and the error tolerance analysis is carried out for accuracy improvement. Application of image processing is carried out using proposed SAET-CSLA.     

Power Reduction Technique in Coefficient Multiplications Through Multiplier Characterization

This paper presents a multiplier power reduction technique for low-power DSP applications through utilization of coefficient optimization. The optimization is implementation dependent in that the multipliers are assumed to be designed in either ASIC or full-custom architectures for general purpose multiplication. The paper first describes a model characterizing the power consumption of the multiplier. Then the coefficient optimized made based on this model. This methodology is applicable to multiplications requiring a large set of coefficients and random data sets. We can accurately estimate the actual power dissipation of the multipliers using the characterization technique. The coefficient optimization based on the power model can save as much as 34.02%.     

Energy-Efficient Multiple-Precision Floating-Point Multiplier for Embedded Applications

Floating-point (FP) multipliers are the main energy consumers in many modern embedded digital signal processing (DSP) and multimedia systems. For lossy applications, minimizing the precision of FP multiplication operations under the acceptable accuracy loss is a well-known approach for reducing the energy consumption of FP multipliers. This paper proposes a multiple-precision FP multiplier to efficiently trade the energy consumption with the output quality. The proposed FP multiplier can perform low-precision multiplication that generates 8?, 14?, 20?, or 26-bit mantissa product through an iterative and truncated modified Booth multiplier. Energy saving for low-precision multiplication is achieved by partially suppressing the computation of mantissa multiplier. In addition, the proposed multiplier allows the bitwidth of mantissa in the multiplicand, multiplier, and output product to be dynamically changed when it performs different FP multiplication operations to further reduce energy consumption. Experimental results show that the proposed multiplier can achieve 59 %, 71 %, 73 %, and 82 % energy saving under 0.1 %, 1 %, 5 %, and 11 % accuracy loss, respectively, for the RGB-to-YUV & YUV-to-RGB conversion when compared to the conventional IEEE single-precision multiplier. In addition, the results also exhibit that the proposed multiplier can obtain more energy reduction than previous multiple-precision iterative FP multipliers.     

Low-Energy Digit-Serial/Parallel Finite Field Multipliers

Digit-serial architectures are best suited for systems requiring moderate sample rate and where area and power consumption are critical. This paper presents a new approach for designing digit-serial/parallel finite field multipliers. This approach combines both array-type and parallel multiplication algorithms, where the digit-level array-type algorithm minimizes the latency for one multiplication operation and the parallel architecture inside of each digit cell reduces both the cycle-time as well as the switching activities, hence power consumption. By appropriately constraining the feasible primitive polynomials, the mod p(x) operation involved in finite field multiplication can be performed in a more efficient way. As a result, the computation delay and energy consumption of one finite field multiplication using the proposed digit-serial/parallel architectures are significantly less than of those obtained by folding the parallel semi-systolic multipliers. Furthermore, their energy-delay products are reduced by a even larger percentage. Therefore, the proposed digit-serial/parallel architectures are attractive for both low-energy and high-performance applications.     

Reconfigurable Rounding Based Approximate Multiplier for Energy Efficient Multimedia Applications

The approximate design has emerged as a revolutionary design paradigm to obtain energy efficient digital signal processing cores while exhibiting acceptable accuracy. In different signal processing architectures, multiplier is the prime arithmetic unit and significantly influences the performance of these cores. Therefore, four novel energy efficient rounding based approximate (RBA) multiplier architectures are proposed in this paper. These multipliers first approximate input operands to the nearest power of two values and then achieve multiplication using few adders and shifters. The proposed RBA multipliers significantly reduce implementation complexity and provide higher energy efficiency. Further, a novel reconfigurable rounding based approximate (RRBA) multiplier is proposed to achieve desired performance-quality tradeoff. Further, the performance of proposed RBA and RRBA multipliers is evaluated and analysed over the existing approximate multiplier architectures. The proposed 8-bit RBA0 requires 59.8% (54.7%) reduced area (delay) compared to the existing approximate multiplier. Finally, the efficacy of the proposed multipliers is demonstrated in the application by implementing Gaussian filters embedded with existing and proposed approximate multipliers. The Gaussian filter designed using RBA0 provides 32.5% reduced energy consumption over the filter with existing multiplier.

     

基于DSP的导引头伺服平台控制器系统电源设计

由于目前高性能DSP系统在降低功耗的同时必须考虑其外围器件的电源特性,所以对DSP系统电路提供电源时必须要考虑到DSP两种电压的供电特性。介绍一种基于DSP的导引头伺服平台控制器电路的电源设计方案。详细给出采用高效率的电压转换芯片为DSP提供核电压、I/O接口电压的应用电路;并设计电源监控与复位电路,以确保供电系统的稳定、可靠和高效。测试表明该电源系统具有较强的实用性和通用性,可以应用于一般的数字伺服控制系统。     

Modified Booth pipelined multiplication

A pipelined modified Booth multiplication is proposed for low power, high performance DSP application. The proposed multiplication is suitable for VLSI implementation. It has a better power-performance ratio than the traditional pipelined multiplier and modified Booth multiplier     

Folded Architecture for Digital Gammatone Filter Used in Speech Processor of Cochlear Implant

Emerging trends in the area of digital very large scale integration (VLSI) signal processing can lead to a reduction in the cost of the cochlear implant. Digital signal processing algorithms are repetitively used in speech processors for filtering and encoding operations. The critical paths in these algorithms limit the performance of the speech processors. These algorithms must be transformed to accommodate processors designed to be high speed and have less area and low power. This can be realized by basing the design of the auditory filter banks for the processors on digital VLSI signal processing concepts. By applying a folding algorithm to the second‐order digital gammatone filter (GTF), the number of multipliers is reduced from five to one and the number of adders is reduced from three to one, without changing the characteristics of the filter. Folded second‐order filter sections are cascaded with three similar structures to realize the eighth‐order digital GTF whose response is a close match to the human cochlea response. The silicon area is reduced from twenty to four multipliers and from twelve to four adders by using the folding architecture.     

A high performance hardware architecture for portable,low-power retinal vessel segmentation

The retina of the human eye and more particularly the retinal blood vasculature can be used in several medical and biometric applications. The use of retinal images in such applications however, is computationally intensive, due to the high complexity of the algorithms used to extract the vessels from the retina. In addition, the emergence of portable biometric authentication applications, as well as onsite biomedical diagnostics raises the need for real-time, power-efficient implementations of such algorithms that can also satisfy the performance and accuracy requirements of portable systems that use retinal images. In an attempt to meet those requirements, this work presents a VLSI implementation of a retina vessel segmentation system while exploring various parameters that affect the power consumption, the accuracy and performance of the system. The proposed design implements an unsupervised vessel segmentation algorithm which utilizes matched filtering with signed integers to enhance the difference between the blood vessels and the rest of the retina. The design accelerates the process of obtaining a binary map of the vessels tree by using parallel processing and efficient resource sharing, achieving real-time performance. The design has been verified on a commercial FPGA platform and exhibits significant performance improvements (up to 90×) when compared to other existing hardware and software implementations, with an overall accuracy of 92.4%. Furthermore, the low power consumption of the proposed VLSI implementation enables the proposed architecture to be used in portable systems, as it achieves an efficient balance between performance, power consumption and accuracy.     

Framework for Digital Filter Design Optimization (DiFiDOT) using MCM Based Register Minimization Retiming for Noise Removal ECG Filters

In all the DSP(Digital Signal Processing) blocks such as digital filters, the filter coefficients are known before hand. Hence, full flexibility of the multiplier is not necessary. Multiplierless Multiple Constant Multiplication(MCM) technique can be used along with retiming for better digital filter optimization.This method is more efficient when compared to shift and add multiplications as intermediate results in MCM technique can be shared which reduces the area of multiplierless implementation of digital filters. The multiplierless filter circuit is further retimed to reduce the overall clock period which increases the clock frequency. Critical path and shortest path computations consume most of the time in retiming computation. The retiming minimizes the overall clock period by reducing the filter critical path. In the general purpose processor where actual retiming vectors are computed for digital filters, the speed with which the retiming transformation is performed suffers as the entire transformation code will be written in the form of a soft core. Hence, FPGA based path solver architecture are proposed in this paper can reduces the burden on general purpose processors while retiming. This work contributes to reduced processing time for retiming using FPGA based path solvers. Due to complexity and transistor size reduction, designing of VLSI architectures for DSP blocks has become very challenging. Automated Tools are required most often to introduce the products to market in a timely manner and to make the VLSI designs more stable, reliable and tractable. A framework called DiFiDOT(Digital Filter Design Optimization Tool) is developed in this work for synthesizing the optimized filter architectures. Finally, an application for Electrocardiography(ECG) is designed using MCM based retimed digital filters to remove the power supply interference, baseline drift and the broadband noise from the ECG signal.     

Low-complexity bit-parallel systolic multipliers over GF(2)

This paper presents new time-dependent and time-independent multiplication algorithms over finite fields GF(2^m) by employing an interleaved conventional multiplication and a folded technique. The proposed algorithm allows efficient realization of the bit-parallel systolic multipliers. The results show that the proposed time-independent multiplier saves about 54% space complexity as compared to other related multipliers for polynomial and dual bases of GF(2^m). The proposed architectures include the features of regularity, modularity and local interconnection. Accordingly, it is well suited for VLSI implementation.     

Comparison of adaptive body bias (ABB) and adaptive supply voltage (ASV) for improving delay and leakage under the presence of process variation

Process variations as a percentage of nominal delay and power consumption are becoming more and more severe with continuing scaling of VLSI technology. The worsening process variation causes increased variability in performance, power, and reliability of VLSI circuits. Thus, performance and power consumption targets obtained during the design phase of VLSI circuits may significantly deviate from that of actual silicon resulting in significant yield losses. Adaptive body bias (ABB) has been shown to be an effective method of postsilicon tuning to reduce variability under the presence of process variation. Post silicon tuning can also be accomplished by using adaptive supply voltage (ASV). This paper compares the effectiveness of ABB and ASV in reducing variability and improving performance and power, and thus, yield.     

High speed merged array multiplication

Multiplication-accumulation operations described by represent the fundamental computation involved in many digital signal processing algorithms. For high speed signal processing, one obvious approach to realize the above computation in VLSI is to employm discrete multipliers working in parallel. However, a more area efficient approach is offered by the merged multiplication technique [5]. But the principal drawback of the conventional merged technique is its longer latency than the former discrete approach. This work proposes a hardware algorithm for merged array multiplication which eliminates this drawback and achieves significant improvement in latency when compared with the conventional scheme for merged multiplication. The proposed algorithm utilizes multiple wave front computation as opposed to the traditional approach where computation in an array multiplier is carried out by a single wave front. The improvement in latency by the proposed approach is greater than 40% (form>2) when compared with a conventional approach to merged multiplication. The consequent cost in the form of additional requirement of VLSI area is found to be rather small. In this paper, we provide a thorough analytic discussion on the proposed algorithm and support it by experimental results.     

Design and Enactment of Diverse Low Power Techniques Based Schmitt Trigger

In the present-day VLSI system, low power design plays a noteworthy role. As we know that, a circuit with higher power consumption can ruin the performance of the system because in the modern world most of the systems are portable. Subsequently, they are functioned by the batteries. Therefore, it is desirable to have a system which operates at lower supply voltages along with maintaining the performance of the system. This low power system can be attained by abating the leakages of the devices up-to an enormous magnitude. In the contemporary VLSI system, a major role is being contributed by the Schmitt trigger circuit. Schmitt trigger is fundamentally a comparator. It is implemented by using a positive feedback. The Schmitt trigger circuit is used in various devices such as buffer, sub-threshold SRAM, sensors and PWM circuit. It is also used in analog to digital converter. The most significant property of the Schmitt trigger is that they provide hysteresis in their voltage transfer curve. Consequently, they provide better noise immunity as compared to their counterparts. Therefore it becomes quite important to enhance the performance of the Schmitt trigger circuit. The power dissipation of the device can be minimized by minimizing the sub-threshold current. The Schmitt trigger circuit is very imperative in producing a clean pulse from the input signal comprising of noise. There are various applications of Schmitt trigger circuit such as in scheming the oscillator circuit, analog to digital converter, function generator, signal conditioning and numerous applications. Thus, it becomes noteworthy to boost its performance by plummeting the leakages and power consumption of the Schmitt trigger circuit. We have realized the Schmitt trigger circuit by the use of FinFET. Therefore, we have got some optimum output in the parameters such as hysteresis width, power consumption and total noise of the Schmitt trigger circuit, but the leakages have been augmented. Thereafter, we have implemented several techniques on the Schmitt trigger circuit to shrink the leakage current, leakage power and other parameters further. We have applied Self Controllable Voltage Level, Adaptive voltage level and MTCMOS technique on the Schmitt trigger circuit using FinFET to further augment the presentation. All the circuits have been simulated in the virtuoso tool of the cadence in 45 nm VLSI domain. We have applied 0.7 V of the supply voltage to perform the simulation and got some tremendous outcome.     

VLSI Implementation of Double-Precision Floating-Point Multiplier Using Karatsuba Technique

The double-precision floating-point arithmetic, specifically multiplication, is a widely used arithmetic operation for many scientific and signal processing applications. In general, the double-precision floating-point multiplier requires a large 53×53 mantissa multiplication in order to get the final result. This mantissa multiplication exists as a limit on both area and performance bounds of this operation. This paper presents a novel way to reduce this large multiplication. The proposed approach in this paper allows to use less amount of multiplication hardware compared to the traditional method. The multiplication is done by using Karatsuba technique. This design is specifically targeting Field Programmable Gate Array (FPGA) platforms, and it has also been evaluated on ASIC flow. The proposed module gives excellent performance with efficient use of resources. The design is fully compatible with the IEEE standard precision. The proposed module has shown a better performance in comparison with the best reported multipliers in the literature.