High-speed, low-power, bipolar standard cell design methodology forGbit/s signal processing

A low-power Si bipolar standard cell LSI design methodology for gigabit/second signal processing is described. To obtain high-speed operation, it features a pair of differential clock channels inside cells, differential clock distribution with the placement of differential wires of equal length and load, a performance-driven layout, and a highly accurate static timing analysis. A computer-aided-design-based optimization technology for power dissipation makes cell currents minimum while maintaining the circuit speed. A 5.6-K gate synchronous digital hierarchy signal-processing LSI operating at 1.6 Gbit/s with only 3.9 W power consumption demonstrates the effectiveness of this design method     

Hybrid asynchronous circuit generation amenable to conventional EDA flow

This work proposes a new method of synthesizing asynchronous circuits targeting its practical usability. The key contribution of this work is finding an effective technique of inter-mixing the two design principles namely handshaking based single-rail and timing annotated (i.e., quasi-delay insensitive (QDI)) dual-rail of asynchronous circuits. Precisely, we propose a clever way of partitioning an input (synchronous) circuit to transform it into a circuit with single-rail and dual-rail sub-circuits and of designing seamless interface to stitch the sub-circuits. Our proposed synthesis flow closely links to industrial design automation tools with standard cell libraries to enhance the practicality and productivity. Experimental results show that the designs produced by our approach expose partial or full combinations of high-performance, low-power consumption, great immunity to delay and noise variability, and mitigation to the side-channel attacks in hardware security.     

A 1-V 2.5-mW 5.2-GHz frequency divider in a 0.35-/spl mu/m CMOS process

A 1-V low-power high-speed dynamic-loading frequency divider is proposed using novel D flip-flops with a common-gate topology and with a single clock phase. A simple and accurate small-signal analysis model is provided to estimate the operating frequencies of the divider. Implemented in a standard digital 0.35-/spl mu/m CMOS process and at 1-V supply, the proposed frequency divider measures a maximum operating frequency up to 5.2 GHz with a power consumption of 2.5 mW.     

Low-Power Programmable FPGA Routing Circuitry

We consider circuit techniques for reducing field-programmable gate-array (FPGA) power consumption and propose a family of new FPGA routing switch designs that are programmable to operate in three different modes: high-speed, low-power, or sleep. High-speed mode provides similar power and performance to traditional FPGA routing switches. In low-power mode, speed is curtailed in order to reduce power consumption. Leakage is reduced by 28%–52% in low-power versus high-speed mode, depending on the particular switch design selected. Dynamic power is reduced by 28%–31% in low-power mode. Leakage power in sleep mode, which is suitable for unused routing switches, is 61%–79% lower than in high-speed mode. Each of the proposed switch designs has a different power/area/speed tradeoff. All of the designs require only minor changes to a traditional routing switch and involve relatively small area overhead, making them easy to incorporate into current commercial FPGAs. The applicability of the new switches is motivated through an analysis of timing slack in industrial FPGA designs. It is observed that a considerable fraction of routing switches may be slowed down (operate in low-power mode), without impacting overall design performance.      

Constant-ratio-coupled multi-grain digital synchronizer with flexible input-output delay selection for versatility in low-power applications

The constant-ratio-coupled multi-grain digital synchronizer (CRC-MGsynchronizer) is proposed as a means for making high-speed connections with very low power consumption, both among multiple chips such as processors, controllers, and storage devices, and among on-chip modules. The synchronizer not only provides a wide range of operating frequencies, but is fast locking and only occupies a small area on chip. Therefore, it contributes to large reductions in power consumption and costs. It is suitable for use in various low-power systems (e.g., battery-hungry mobile appliances and low-cost consumer electronic products). Three major techniques were applied to the design: 1)a multi-grain structure for the delay elements, which greatly reduces the number of gates while facilitating locking in a very small number of clock cycles;2) constant-ratio-coupled (CRC) delay lines (measurement versus generation)for flexible selection of the input-output delay; and 3) a new lock stage decision circuit (LSDC) scheme, conferring excellent testability. Moreover,the architecture is all-digital, and thus it has high process portability. By applying these techniques to a DDR memory interface circuit for a mobile application processor fabricated in 130-nm technology, we were able to reduce power consumption by 42% and chip area by 65% compared with a conventional implementation. Furthermore, the novel design spans a frequency range covering 12 times the minimum frequency.     

Fully boosted 64K dynamic RAM with automatic and self-refresh

A novel high-speed low-power 64K dynamic RAM with enough margin has been attained using a double polysilicon and 3-/spl mu/m process technologies. To obtain a low soft error rate below 1/spl times/10/SUP -6/ errors per device hour without sacrificing the high-speed and low-power operation, some novel approaches are proposed in the circuit and device designs. In particular, fully boosted circuits and the Hi-C cell structure with polysilicon bit line are designed to increase the margin of the single 5-V power supply 64K dynamic RAM. The fabricated device provides a typical access time of 90 ns and an operating power of 190 mW at 25/spl deg/C. Also, the design features of the automatic and self-refresh functions on the same chip are described.     

A Current-Mode Logic for Low-Voltage, High-Speed Mixed-Mode VLSI Circuits

A wired-AND current-mode logic (WCML) circuit is designed for high performance mixed analog and digital system designs on a common silicon substrate, using standard CMOS process. Current is used for digital information carrier in order to be able to reduce supply voltage, power consumption, digital switching noise and to increase operating frequency. The WCML circuit uses current-steering technique. It is composed of a simple current mirror with a current injector. Wired-AND connections cause the logic circuit to operate as a NAND logic gate which provides to implement any boolean function. High-speed is achieved by varying the injection current level even at low-voltage supply (<1.5 V) with low-power consumption.     

Double-precision Dual Mode Logic carry-save multiplier

In this paper, a double-precision carry-save adder (CSA)-based array multiplier is designed using the Dual Mode Logic (DML) approach in a commercial 65-nm low-power CMOS technology. DML typically allows on-the-fly controllable switching at the gate level between static and dynamic operation modes. The proposed multiplier exploits this unique ability of DML to efficiently trade performance and energy consumption when considering on-demand double-precision (8 × 8-bit or 16 × 16-bit) operations. This occurs in the DML multiplier working in a mixed operation mode, i.e., by employing the static and dynamic mode for lower and higher precision operations, respectively. In fact, the use of the dynamic mode for higher precision operations ensures higher performance as compared to the standard CMOS circuit (16% gain on average) at the cost of higher energy consumption. Such energy penalty is counterbalanced at lower precision operations where the static mode is enabled in the DML circuit. Overall, the adoption of the mixed operation mode in the proposed DML multiplier proves to be beneficial to achieve a better performance/energy trade-off with respect to the standard CMOS implementation and to the case when using either the static or the dynamic mode for both operations at the two different precisions. When compared to its CMOS counterpart, our DML design operating in the mixed mode exhibits an average improvement of 15% in terms of energy-delay product (EDP) under wide-range supply voltage scaling. Such benefit is maintained over process-voltage-temperature (PVT) variations.     

Dual-modulus 127/128 FOM enhanced prescaler design in 0.35-/spl mu/m CMOS technology

The dual-modulus prescaler is a critical block in CMOS systems like high-speed frequency synthesizers. However, the design of high-moduli, high-speed, and low-power dual-modulus prescalers remains a challenge. To face the challenge, this paper introduces the idea of using transmission gates and pseudo-PMOS logic to realize the dual-modulus prescaler. The topology of the prescaler proposed is different from prior designs primarily in two ways: 1) it uses transmission gates in the critical path and 2) the D flip-flops (DFFs) used in the synchronous counter comprise pseudo-PMOS inverters and ratioed latches. A pseudo-PMOS logic-based DFF is introduced and used in the proposed prescaler design. Based on the proposed topology, a dual-modulus divide-by-127/128 prescaler is implemented in 0.35-/spl mu/m CMOS technology. It consumes 4.8 mW from a 3-V supply. The measured phase noise is -143.4 dBc/Hz at 600 kHz. The silicon area required is only 0.06 mm/sup 2/. There are no flip flops or logic gates in the critical path. This topology is suitable for high-speed and high-moduli prescaler designs. It reduces: 1) design complexity; 2) power consumption; and 3) input loading. Measurement results are provided. An improvement in the figure of merit is shown.     

Design techniques and test methodology for low-power TCAMs

Ternary content addressable memories (TCAMs) are gaining importance in high-speed lookup-intensive applications. However, the high cost and power consumption are limiting their popularity and versatility. TCAM testing is also time consuming due to the complex integration of logic and memory. In this paper, we present a comprehensive review of the design techniques for low-power TCAMs. We also propose a novel test methodology for various TCAM components. The proposed test algorithms show significant improvement over the existing algorithms both in test complexity and fault coverage.     

A portable digitally controlled oscillator using novel varactors

This work presents a portable digitally controlled oscillator (DCO) by using two-input NOR gates as a digitally controlled varactor (DCV) in fine-tuning delay cell design. This novel varactor uses the gate capacitance difference of NOR gates under different digital control inputs to establish a DCV. Thus proposed DCO can improve delay resolution 256 times better than a single buffer design. This study also examines different types of NOR/NAND gates (2-input or 3-input) for DCV. The proposed DCO with novel DCV can be implemented with standard cells, and thus it can be ported to different processes in short time. Furthermore, the final circuit layout can be generated using an auto placement and routing (APR) tools. A test chip demonstrates that LSB resolution of the DCO can be improved to 1.55 ps with standard 0.35-/spl mu/m 2P4M CMOS digital cell library. The proposed DCO has good performance in terms of fine resolution, high portability, and short design turnaround cycle compared with conventional DCO designs.     

A monolithic digital clock-generator for on-chip clocking of customDSP's

This paper shows a robust and easily implemented clock generator for custom designs. It is a fully digital design suitable for both high-speed clocking and low-voltage applications. This clocking method is digital, and it avoids analog methods like phase locked loops or delay line loops. Instead, the clock generator is based on a ring counter which stops a ring oscillator after the correct number of cycles. Both a 385 MHz clock and a 15 MHz custom DSP application using the on-chip clocking strategy are described. The prototypes have been fabricated in a 0.8 μm standard CMOS process. The major advantages with this clocking method are robustness, small size, low-power consumption, and that it can operate at a very low supply voltage     

基于并行完备检测的高速异步流水线设计

为了有效地提升异步零协议逻辑(NCL)流水线的吞吐量,该文提出一种多阈值并行完备流水线。采用独特的半静态零协议阈值门建立异步组合逻辑,使数据串行传输的同时每级流水线数据处理和完备检测并行进行,以串并结合的工作方式提升吞吐量。同时新阈值门的使用降低了流水线空周期时的静态功耗。基于SMIC 0.18μm标准CMOS工艺对所提出的流水线进行了分析测试。与现有流水线比较显示,当组合逻辑为四位串行进位全加器时,新的流水线吞吐量提升62.8%,静态功耗减少40.5%,可用于高速低功耗的异步电路设计。     

Algorithm-based low-power transform coding architectures: themultirate approach

In most low-power VLSI designs, the supply voltage is usually reduced to lower the total power consumption. However, the device speed will be degraded as the supply voltage goes down. In this paper, we propose new algorithmic-level techniques to compensate the increased delays based on the multirate approach. We apply the technique of polyphase decomposition to design low-power transform coding architectures, in which the transform coefficients are computed through decimated low-speed input sequences. Since the operating frequency is M-times slower than the original design while the system throughput rate is still maintained, the speed penalty can be compensated at the architectural level. We start with the design of low-power multirate discrete cosine transform (DCT)/inverse discrete cosine transform (IDCT) VLSI architectures. Then the multirate low-power design is extended to the modulated lapped transform (MLT), extended lapped transform (ELT), and a unified low-power transform coding architecture. Finally, we perform finite-precision analysis for the multirate DCT architectures. The analytical results can help us to choose the optimal wordlength for each DCT channel under required signal-to-noise ratio (SNR) constraint, which can further reduce the power consumption at the circuit level. The proposed multirate architectures can also be applied to very high-speed block discrete transforms in which only low-speed operators are required     

CADRE: An Asynchronous Embedded DSP for Mobile Phone Applications

Asynchronous design techniques have a number of compelling features that make them suited for complex system on chip designs. However, it is necessary to develop practical and efficient design techniques to overcome the present shortage of commercial design tools. This paper describes the development of CADRE (Configurable Asynchronous DSP for Reduced Energy), a 750K transistor, high performance, low-power digital signal processor IP block intended for digital mobile phone chipsets. A short time period was available for the project, and so a methodology was developed that allowed high-level simulation of the design at the earliest possible stage within the conventional schematic entry environment and simulation tools used for later circuit-level performance and power consumption assessment. Initial modeling was based on C behavioral models of the various data and control components, with the many asynchronous control circuits required automatically generated from their specifications. This has enabled design options to be explored and unusual features of the design, such as the Register Bank which is designed to exploit data access patterns, are presented along with the power and performance results of the processor as a whole.     

Designing novel reversible BCD adder and parallel adder/subtraction using new reversible logic gates

Reversible logic has received much attention in recent years when calculation with minimum energy consumption is considered. Especially, interest is sparked in reversible logic by its applications in some technologies, such as quantum computing, low-power CMOS design, optical information processing and nanotechnology. This article proposes two new reversible logic gates, ZRQ and NC. The first gate ZRQ not only implements all Boolean functions but also can be used to design optimised adder/subtraction architectures. One of the prominent functionalities of the proposed ZRQ gate is that it can work by itself as a reversible full adder/subtraction unit. The second gate NC can complete overflow detection logic of Binary Coded Decimal (BCD) adder. This article proposes two approaches to design novel reversible BCD adder using new reversible gates. A comparative result which is presented shows that the proposed designs are more optimised in terms of number of gates, garbage outputs, quantum costs and unit delays than the existing designs.     

A novel high-speed sense amplifier for Bi-NOR flash memories

A novel high-speed current-mode sense amplifier is proposed for Bi-NOR flash memory designs. Program and erasure of the Bi-NOR technologies employ bi-directional channel FN tunneling with localized shallow P-well structures to realize the high-reliability, high-speed, and low-power operation. The proposed sensing circuit with advanced cross-coupled structure by connecting the gates of clamping transistors to the cross-coupled nodes provides excellent immunity against mismatch compared with the other sense amplifiers. Furthermore, the sensing times for various current differences and bitline capacitances and resistances are all superior to the others. The agreement between simulation and measurement indicates the sensing speed reaches 2ns for the threshold voltage difference of lower than 1 V at 1.8-V supply voltage even with the high threshold voltage of the peripheral CMOS transistors up to 0.8 V.     

一种高速低功耗LVDS接收器电路的设计

介绍了LVDS系统链路结构及数据传输原理,分析了LVDS标准对接收器电路的需求,文中基于65 nm 数字CMOS工艺设计,实现了一种高速低功耗LVDS接收器电路。仿真结果表明,在2.5 V电源电压工作下,该LVDS接收器具有2 Gbit·s^-1的数据传输速率,平均功耗为3 mW。     

Design strategies of cascaded CML gates

In this paper, a strategy to design paths consisting of cascaded bipolar current-mode logic gates is proposed. In particular, explicit design criteria are derived both for low-power non-critical paths and high-speed critical paths. The analytical results are simple to be applied to actual circuits avoiding the usual time-consuming approach based on iterative simulations with a trial-and-error procedure. Moreover, it provides the designer with a deeper understanding of the power-delay trade-off. Design examples based on a 20-GHz bipolar process are introduced to validate the procedure and clarify its application.