A Review of Ground-Bouncing-Noise Minimization Techniques in MTCMOS Circuits

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Design of Low Power Data Preserving Flip Flop Using MTCMOS Technique

In order to reduce overall power consumption, a well-known technique is to scale supply voltages. However, to maintain performance, device threshold voltages must scale as well, which will cause sub threshold leakage currents to increase exponentially. The sub threshold voltage has to affect the two parameters one is the delay and other one is the sub threshold leakage current. Smaller the threshold voltage smaller will be delay while larger will be the sub threshold current. Controlling sub threshold leakage has been explored significantly in the literature, especially in the context of reducing leakage currents in burst mode type circuits, where the system spends the majority of the time in an idle standby, or sleep, state where no computation is taking place. MTCMOS or multi-threshold CMOS has been proposed as a very effective technique for reducing leakage currents during the standby by state by utilizing high sleep devices to gate the power supplies of a low logic block. Although MTCMOS circuit techniques are effective for controlling leakage currents in combinational logic, a drawback is that it can cause internal nodes to float, and cannot be directly used in standard memory cells without corrupting stored data. As a result, several researchers have explored possible MTCMOS latch designs that can reduce leakage currents yet maintain state during the standby modes. In this work a data preserving flip flop with reduced leakage power is designed using MTCMOS technique in 90nm technology with the help of CADENCE tool. The simulation results have shown that the leakage power is reduced by 25.70% compared to CMOS flip flop

Addressing On-Chip Power Conversion and Dissipation Issues in Many-Core System-on-a-Chip based on Conventional Silicon and Emerging Nanotechnologies

Title from PDF of title page viewed August 27, 2018Dissertation advisor: Masud H ChowdhuryVitaIncludes bibliographical references (pages 158-163)Thesis (Ph.D.)--School of Computing and Engineering and Department of Physics and Astronomy. University of Missouri--Kansas City, 2017Integrated circuits (ICs) are moving towards system-on-a-chip (SOC) designs. SOC allows various small and large electronic systems to be implemented in a single chip. This approach enables the miniaturization of design blocks that leads to high density transistor integration, faster response time, and lower fabrication costs. To reap the benefits of SOC and uphold the miniaturization of transistors, innovative power delivery and power dissipation management schemes are paramount. This dissertation focuses on on-chip integration of power delivery systems and managing power dissipation to increase the lifetime of energy storage elements. We explore this problem from two different angels: On-chip voltage regulators and power gating techniques. On-chip voltage regulators reduce parasitic effects, and allow faster and efficient power delivery for microprocessors. Power gating techniques, on the other hand, reduce the power loss incurred by circuit blocks during standby mode. Power dissipation (Ptotal = Pstatic and Pdynamic) in a complementary metal-oxide semiconductor (CMOS) circuit comes from two sources: static and dynamic. A quadratic dependency on the dynamic switching power and a more than linear dependency on static power as a form of gate leakage (subthreshold current) exist. To reduce dynamic power loss, the supply power should be reduced. A significant reduction in power dissipation occurs when portions of a microprocessor operate at a lower voltage level. This reduction in supply voltage is achieved via voltage regulators or converters. Voltage regulators are used to provide a stable power supply to the microprocessor. The conventional off-chip switching voltage regulator contains a passive floating inductor, which is difficult to be implemented inside the chip due to excessive power dissipation and parasitic effects. Additionally, the inductor takes a very large chip area while hampering the scaling process. These limitations make passive inductor based on-chip regulator design very unattractive for SOC integration and multi-/many-core environments. To circumvent the challenges, three alternative techniques based on active circuit elements to replace the passive LC filter of the buck convertor are developed. The first inductorless on-chip switching voltage regulator architecture is based on a cascaded 2nd order multiple feedback (MFB) low-pass filter (LPF). This design has the ability to modulate to multiple voltage settings via pulse with modulation (PWM). The second approach is a supplementary design utilizing a hybrid low drop-out scheme to lower the output ripple of the switching regulator over a wider frequency range. The third design approach allows the integration of an entire power management system within a single chipset by combining a highly efficient switching regulator with an intermittently efficient linear regulator (area efficient), for robust and highly efficient on-chip regulation. The static power (Pstatic) or subthreshold leakage power (Pleak) increases with technology scaling. To mitigate static power dissipation, power gating techniques are implemented. Power gating is one of the popular methods to manage leakage power during standby periods in low-power high-speed IC design. It works by using transistor based switches to shut down part of the circuit block and put them in the idle mode. The efficiency of a power gating scheme involves minimum Ioff and high Ion for the sleep transistor. A conventional sleep transistor circuit design requires an additional header, footer, or both switches to turn off the logic block. This additional transistor causes signal delay and increases the chip area. We propose two innovative designs for next generation sleep transistor designs. For an above threshold operation, we present a sleep transistor design based on fully depleted silicon-on-insulator (FDSOI) device. For a subthreshold circuit operation, we implement a sleep transistor utilizing the newly developed silicon-on ferroelectric-insulator field effect transistor (SOFFET). In both of the designs, the ability to control the threshold voltage via bias voltage at the back gate makes both devices more flexible for sleep transistors design than a bulk MOSFET. The proposed approaches simplify the design complexity, reduce the chip area, eliminate the voltage drop by sleep transistor, and improve power dissipation. In addition, the design provides a dynamically controlled Vt for times when the circuit needs to be in a sleep or switching mode.Introduction -- Background and literature review -- Fully integrated on-chip switching voltage regulator -- Hybrid LDO voltage regulator based on cascaded second order multiple feedback loop -- Single and dual output two-stage on-chip power management system -- Sleep transistor design using double-gate FDSOI -- Subthreshold region sleep transistor design -- Conclusio

Integrated Circuits and Systems for Smart Sensory Applications

Connected intelligent sensing reshapes our society by empowering people with increasing new ways of mutual interactions. As integration technologies keep their scaling roadmap, the horizon of sensory applications is rapidly widening, thanks to myriad light-weight low-power or, in same cases even self-powered, smart devices with high-connectivity capabilities. CMOS integrated circuits technology is the best candidate to supply the required smartness and to pioneer these emerging sensory systems. As a result, new challenges are arising around the design of these integrated circuits and systems for sensory applications in terms of low-power edge computing, power management strategies, low-range wireless communications, integration with sensing devices. In this Special Issue recent advances in application-specific integrated circuits (ASIC) and systems for smart sensory applications in the following five emerging topics: (I) dedicated short-range communications transceivers; (II) digital smart sensors, (III) implantable neural interfaces, (IV) Power Management Strategies in wireless sensor nodes and (V) neuromorphic hardware

Out-of-band transfer with Android to configure pre-shared secrets into sensor nodes

Applications based on Wireless Sensor Networks are making their way into all kinds of industries. Today, they can do anything from off-loading hospitals by monitoring patients in their homes to regulating production lines in factories. More often than not, they perform some kind of surveillance and tracking. Thus, in most cases the information they carry is sensitive, rendering good encryption schemes suited for performance-constrained sensor nodes a valuable commodity. As traditional encryption is not well suited for performance constrained environments, there are many new "lightweight" encryption schemes emerging. However, many of the popular up and coming schemes make the assumption of already having a pre-shared secret available in the sensor node beforehand which can act as the base for their encryption key. The procedure of configuring this pre-shared secret into the sensor node is crucial and has the potential of breaking any scheme based on that assumption. Therefore, we have looked at different procedures of configuring this pre-shared secret into a sensor node securely, using nothing more than a smartphone to configure the sensor node. This would eventually eliminate the assumption of how the pre-shared secret got into the sensor node in the first place. We used an Arduino Uno R3 running an Atmega328p MCU as a simulation of a potential sensor node. Moreover, using a smartphone as the configuration device, we chose to base the communication on two types of OOB based side-channels; Namely, a visual-based using the flashlight and screen as well as audio-based, using the loudspeaker. We concluded that using a smartphone as configuration device has its difficulties, although, in this specific environment it is still a viable choice. The solution can decrease the previous knowledge required by the user performing the configuration while simultaneously upholding a high security level. The findings of this thesis highlight the fact that: technology has evolved to a point where the smartphones of today can outperform the specialized devices of yesterday. In other words, solutions previously requiring specialized hardware can today be achieved with much less "specialized" equipment. This is desirable because with less specialized equipment, it becomes easier to further develop and improve a system like this, increasing its viability.Have you ever wondered what would happen if somebody could access your refrigerator? Might seem silly, but how about your front door's lock? With the ever increasing connected society, you might have to think about these questions sooner rather than later. The establishment of our connected society is heavily dependent on sensor nodes. There is currently no rigid way of loading the necessary cryptographic keys into these sensor nodes. Now, to enable these sensor nodes to communicate securely, we have studied alternative ways of using your smartphone to transmit these keys to the sensor nodes. In this thesis, we have shown alternative ways of using a smartphone to transmit cryptographic keys into sensor nodes. These alternative ways were achieved by using components not otherwise thought to be used for communication. For instance, we built prototypes that used the flashlight; the screen and the loudspeaker to successfully transmit the keys. Doing this we were able to make the transmission easy to use while at the same time upholding a high level of security. Currently, the sensor nodes have many protocols available to use for secure communications. However, these protocols often lack information about how one should load the sensor nodes with the keys, to begin with. In essence, they provide you with the car but not the key to start it. This is a problem that needs a concrete solution. The result of this thesis can be used as a guideline for further development of this type of solution. Our prototypes indicate that this type of solution is not only viable but can be secure as well. Using nothing more than a smartphone and small additions to the sensor nodes hardware. Briefly, the prototypes are built using an Android-powered smartphone as "key-transmitting device" while the receiving "sensor node" is equipped with a microphone or a photo-transistor. The additions to the receiver enable detection of both light and sound waves sent from the smartphone. Then, using the smartphone, the user is able to transmit data by blinking with the flashlight or screen; or sending tones with the loudspeaker, which the receiver interprets

Circuit and System Level Design Optimization for Power Delivery And Management

As the VLSI technology scales to the nanometer scale, power consumption has become a critical design concern of VLSI circuits. Power gating and dynamic voltage and frequency scaling (DVFS) are two effective power management techniques that are widely utilized in modern chip designs. Various design challenges merge with these power management techniques in nanometer VLSI circuits. For example, power gating introduces unique power integrity issues and trade-offs between switching noise and rush current noise. Assuring power integrity and achieving power efficiency are two highly intertwined design challenges. In addition, these trade-offs significantly vary with the supply voltage. It is difficult to use conventional power-gated power delivery networks (PDNs) to fully meet the involved conflicting design constraints while maximizing power saving and minimizing supply noise. The DVFS controller and the DC-DC power converter are two highly intertwining enablers for DVFS-based systems. However, traditional DVFS techniques treat the design optimizations of the two as separate tasks, giving rise to sub-optimal designs. To address the above research challenges, we propose several circuit and system level design optimization techniques in this dissertation. For power-gated PDN designs, we propose systemic decoupling capacitor (decap) optimization strategies that optimally trade-off between power integrity and leakage saving. First, new global decap and re-routable decap design concepts are proposed to relax the tight interaction between power integrity and leakage power saving of power-gated PDN at a single supply voltage level. Furthermore, we propose to leverage re-routable decaps to provide flexible decap allocation structures to better suit multiple supply voltage levels. The proposed strategies are implemented in an automatic design flow for choosing optimal amount of local decaps, global decaps and re-routable decaps. The proposed techniques significantly increase leakage saving without jeopardizing power integrity. The flexible decap allocations enabled by re-routable decaps lead to optimal design trade-offs for PDNs operating with two supply voltage levels. To improve the effectiveness of DVFS, we analyze the drawbacks of circuit-level only and policy-level only optimizations and the promising opportunities resulted from the cross-layer co-optimization of the DC-DC converter and online learning based DVFS polices. We present a cross-layer approach that optimizes transition time, area, energy overhead of the DC-DC converter along with key parameters of an online learning DVFS controller. We systematically evaluate the benefits of the proposed co-optimization strategy based on several processor architectures, namely single and dual-core processors and processors with DVFS and power gating. Our results indicate that the co-optimization can introduce noticeable additional energy saving without significant performance degradation