A 10-bit 40MS/s Pipelined ADC in a 0.13μm CMOS Process

This paper presents a 10-bit analogue to digital converter (ADC) that will be integrated in a general purpose charge readout ASIC that is the new generation of mixed-mode integrated circuits for Time Projection Chamber (TPC) readout. It is based on a pipelined structure with double sampling and was implemented with switched capacitor circuits in eight 1.5-bit stages followed by a 2-bit stage. The power consumption is adjustable with the conversion rate and varies between 15 and 34mW for a 15 to 40MS/s conversion speed. The ADC occupies a silicon area of 0.7mm2 in a 0.13μm CMOS process and operates from a single 1.5V supply

A Multi-Gigahertz Analog Transient Recorder Integrated Circuit

A monolithic multi-channel analog transient recorder, implemented using switched capacitor sample-and-hold circuits and a high-speed analogically-adjustable delay-line-based write clock, has been designed, fabricated and tested. The 2.1 by 6.9 mm layout, in 1.2 micron CMOS, includes over 31,000 transistors and 2048 double polysilicon capacitors. The circuit contains four parallel channels, each with a 512 deep switched-capacitor sample-and-hold system. A 512 deep edge sensitive tapped active delay line uses look-ahead and 16 way interleaving to develop the 512 sample and hold clocks, each as little as 3.2 ns wide and 200 ps apart. Measurements of the device have demonstrated 5 GHz maximum sample rate, at least 350 MHz bandwidth, an extrapolated rms aperture uncertainty per sample of 0.7 ps, and a signal to rms noise ratio of 2000:1.Comment: 64 pages, 17 figures. Thesis, University of California, Berkeley, 199

Power-efficient high-speed interface circuit techniques

Inter- and intra-chip connections have become the new challenge to enable the scaling of computing systems, ranging from mobile devices to high-end servers. Demand for aggregate I/O bandwidth has been driven by applications including high-speed ethernet, backplane micro-servers, memory, graphics, chip-to-chip and network onchip. I/O circuitry is becoming the major power consumer in SoC processors and memories as the increasing bandwidth demands larger per-pin data rate or larger I/O pin count per component. The aggregate I/O bandwidth has approximately doubled every three to four years across a diverse range of standards in different applications. However, in order to keep pace with these standards enabled in part by process-technology scaling, we will require more than just device scaling in the near future. New energy-efficient circuit techniques must be proposed to enable the next generations of handheld and high-performance computers, given the thermal and system-power limits they start facing. ^ In this work, we are proposing circuit architectures that improve energy efficiency without decreasing speed performance for the most power hungry circuits in high speed interfaces. By the introduction of a new kind of logic operators in CMOS, called implication operators, we implemented a new family of high-speed frequency dividers/prescalers with reduced footprint and power consumption. New techniques and circuits for clock distribution, for pre-emphasis and for driver at the transmitter side of the I/O circuitry have been proposed and implemented. At the receiver side, new DFE architecture and CDR have been proposed and have been proven experimentally

DESIGN AND IMPLEMENTATION OF AN ALL-COTS DIGITAL BACK-END FOR A PULSE-DOPPLER SYNTHETIC APERTURE RADAR

Radar imaging techniques employing synthetic aperture radar (SAR) are ubiquitous in applications such as defense, remote sensing, space exploration, terrain mapping, and many others. However, to obtain fine image resolution, radar systems must be capable of utilizing large signal bandwidths. By the sampling theorem, a large signal bandwidth equates to a high sampling frequency, resulting in more expensive and complex digital electronics required to digitize and process the waveform. Using linear frequency modulated (LFM) pulses and stretch processing techniques, systems such as frequency-modulated continuous-wave (FMCW) radars reduce the required sampling rate at the expense of longer pulses, higher transmit duty cycle, and decreased pulse repetition frequency. While these tradeoffs are often acceptable, in many situations they are not, and a pulse-Doppler radar system is required. These systems can utilize LFM pulses with nearly any desired pulse length and pulse repetition frequency to perform imaging, but they must have an analog-to-digital converter (ADC) and back-end processing capable of handling the full waveform bandwidth, leading to increased cost, size, or both. At the University of Oklahoma’s Advanced Radar Research Center, a pulse-Doppler radar system for use in a SAR application is designed and built using only commercially available components to decrease the size and cost of the radar, specifically the digital back-end. A minimum size and weight is targeted for this system because it is desired to eventually fly the radar and form images on a lightweight airborne platform, such as a quad- or octo-copter. The challenge with using commercial parts for a custom digital pulse-Doppler radar is that it is difficult to meet the strict timing requirements inherent to pulse-Doppler radar while simultaneously meeting the high-bandwidth requirements imposed by SAR. In this thesis, the design and implementation of the digital back-end for the custom SAR system is presented. The focus is placed on designing a control system and clock distribution scheme in the digital back-end to ensure pulse to pulse coherence while maintaining ideal LFM spectral quality. Additionally, a calibration method is devised to provide accurate range measurements each time the radar is turned on even if the latency between the digital transmitter and receiver changes. At the conclusion of this work, it is shown that the radar system is capable of performing accurate pulse-Doppler radar through the generation of range-Doppler maps from data captured by the radar. The results of these tests indicate that the system is suitable for eventual use in SAR imaging applications

Power Reduction Techniques in Clock Distribution Networks with Emphasis on LC Resonant Clocking

In this thesis we propose a set of independent techniques in the overall concept of LC resonant clocking where each technique reduces power consumption and improve system performance. Low-power design is becoming a crucial design objective due to the growing demand on portable applications and the increasing difficulties in cooling and heat removal. The clock distribution network delivers the clock signal which acts as a reference to all sequential elements in the synchronous system. The clock distribution network consumes a considerable amount of power in synchronous digital systems. Resonant clocking is an emerging promising technique to reduce the power of the clock network. The inductor used in resonant clocking enables the conversion of the electric energy stored on the clock capacitance to magnetic energy in the inductor and vice versa. In this thesis, the concept of the slack in the clock skew has been extended for an LC fully-resonant clock distribution network. This extra slack in comparison to standard clock distribution networks can be used to reduce routing complexity, achieve reduction in wire elongation, total wire length, and power consumption. Simulation results illustrate that by utilizing the proposed approach, an average reduction of 53% in the number of wire elongations and 11% reduction in total wire length can be achieved. A dual-edge clocking scheme introduced in the literature to enable the operation of the flip-flop at the rising- and falling edges of the clock has been modified. The interval by which the charging elements in the flip-flop are being switched-on was reduced causing a reduction in power consumption. Simulating the flip-flop in STMicroelectronics 90-nm technology shows correct functionality of the Sense Amplifier flip-flop with a resonant clock signal of 500 MHz and a throughput of 1 GHz under process, voltage, and temperature (PVT) variations. Modeling the resonant system with the proposed flip-flop illustrates that dual-edge compared to single-edge triggering can achieve up to 58% reduction in power consumption when the clock capacitance is the dominating factor. The application of low-swing clocking to LC resonant clock distribution network has been investigated on-chip. The proposed low-swing resonant clocking scheme operates with one voltage supply and does not require an additional supply voltage. The Differential Conditional Capturing flip-flop introduced in the literature was modified to operate with a low-swing sinusoidal clock. Low-swing resonant clocking achieved around 5.8% reduction in total power with 5.7% area overhead. Modeling the clock network with the proposed flip-flop illustrates that low-swing clocking can achieve up to 58% reduction in the power consumption of the resonant clock. An analytical approach was introduced to estimate the required driver strength in the clock generator. Using the proposed approach early in the design stage reduces area and power overhead by eliminating the need for programmable switches in the driving circuit

Energy-Efficient Neural Network Architectures

Emerging systems for artificial intelligence (AI) are expected to rely on deep neural networks (DNNs) to achieve high accuracy for a broad variety of applications, including computer vision, robotics, and speech recognition. Due to the rapid growth of network size and depth, however, DNNs typically result in high computational costs and introduce considerable power and performance overheads. Dedicated chip architectures that implement DNNs with high energy efficiency are essential for adding intelligence to interactive edge devices, enabling them to complete increasingly sophisticated tasks by extending battery lie. They are also vital for improving performance in cloud servers that support demanding AI computations. This dissertation focuses on architectures and circuit technologies for designing energy-efficient neural network accelerators. First, a deep-learning processor is presented for achieving ultra-low power operation. Using a heterogeneous architecture that includes a low-power always-on front-end and a selectively-enabled high-performance back-end, the processor dynamically adjusts computational resources at runtime to support conditional execution in neural networks and meet performance targets with increased energy efficiency. Featuring a reconfigurable datapath and a memory architecture optimized for energy efficiency, the processor supports multilevel dynamic activation of neural network segments, performing object detection tasks with 5.3x lower energy consumption in comparison with a static execution baseline. Fabricated in 40nm CMOS, the processor test-chip dissipates 0.23mW at 5.3 fps. It demonstrates energy scalability up to 28.6 TOPS/W and can be configured to run a variety of workloads, including severely power-constrained ones such as always-on monitoring in mobile applications. To further improve the energy efficiency of the proposed heterogeneous architecture, a new charge-recovery logic family, called zero-short-circuit current (ZSCC) logic, is proposed to decrease the power consumption of the always-on front-end. By relying on dedicated circuit topologies and a four-phase clocking scheme, ZSCC operates with significantly reduced short-circuit currents, realizing order-of-magnitude power savings at relatively low clock frequencies (in the order of a few MHz). The efficiency and applicability of ZSCC is demonstrated through an ANSI S1.11 1/3 octave filter bank chip for binaural hearing aids with two microphones per ear. Fabricated in a 65nm CMOS process, this charge-recovery chip consumes 13.8µW with a 1.75MHz clock frequency, achieving 9.7x power reduction per input in comparison with a 40nm monophonic single-input chip that represents the published state of the art. The ability of ZSCC to further increase the energy efficiency of the heterogeneous neural network architecture is demonstrated through the design and evaluation of a ZSCC-based front-end. Simulation results show 17x power reduction compared with a conventional static CMOS implementation of the same architecture.PHDElectrical and Computer EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147614/1/hsiwu_1.pd

Python based FPGA design-flow

This dissertation undertakes to establish the feasibility of using MyHDL as a basis on which to develop an FPGA-based DSP tool-ow to target CASPER hardware. MyHDL is an open-source package which enables Python to be used as a hardware definition and verification language. As Python is a high-level language, hardware designers can use it to model and simulate designs, without needing detailed knowledge of the underlying hardware. MyHDL has the ability to convert designs to Verilog or VHDL allowing it to integrate into the more traditional design-ow. The CASPER tool- ow exhibits limitations such as design environment instability and high licensing fees. These shortcomings are addressed by MyHDL. To enable CASPER to take advantage of its powerful features, MyHDL is incorporated into a next generation tool-ow which enables high-level designs to be fully simulated and implemented on the CASPER hardware architectures