Adjustable Circuit Research Articles

Open-Loop Fractional Division Using a Voltage-Comparator-Based Digital-to-Time Converter

An open-loop fractional divider is proposed to eliminate the deterministic jitter caused by the conventional fractional dividers without additional calibration. The proposed divider utilizes a new voltage-comparator-based digital-to-time converter (DTC) as an adjustable delay circuit to control the edges of the output clock of the divider. The proposed DTC proves to be power efficient considering its resolution and the frequency of the output clock. Detailed analysis of non-idealities of the proposed architecture and its effect on the cancellation of the deterministic jitter are presented and verified by simulations. Simulation results show that for an input frequency of 5.325 GHz and an output frequency of 1 GHz, the proposed divider achieves 0.2 ps of time resolution using a 10-bit DTC while consuming 3.72 and 1.17 mW from 1.2- and 0.9-V supply for 130- and 65-nm CMOS technology nodes, respectively.

The use of the AVERT system to limit contrast volume administration during peripheral angiography and intervention.

The AVERT(TM) Contrast Modulation System (AVERT) (Osprey Medical, MN) is designed to reduce contrast volume administration during angiography. The AVERT provides an adjustable resistance circuit which decreases the pressure head delivering contrast towards the patient. The AVERT has not been previously studied in patients undergoing peripheral digital subtraction angiography (DSA). The purpose of this study was (1) to evaluate contrast savings with the AVERT and (2) to evaluate the ability to generate clinically acceptable DSA images in the process. To better define the mechanism of action in the peripheral circulation, we also developed a bench model to study the effects of the AVERT on the hydrodynamics of contrast delivery. Patients undergoing lower extremity DSA (diagnostic or intervention, sheath or catheter) were studied. The following variables were recorded for each injection: starting control syringe contrast volume, contrast volume injected towards patient, contrast volume returned to AVERT reservoir, net contrast administered to the patient and % savings. The AVERT resistance was adjusted manually based on operator's discretion--balancing image quality and contrast savings. About 408 DSA angiographic sequences were obtained in 22 patients undergoing 29 procedures. Almost 68% of the patients had chronic kidney disease. An 82% presented with critical limb ischemia, 18% had claudication. There was an overall 37% ± 14% savings of contrast (31% for diagnostic DSA, 40% for interventional procedures). Overall 91% of all images were acceptable for clinical decision making. Specifically, 94% of diagnostic and 87% of interventional images were acceptable. Injection through a 4 Fr catheter (77% acceptable) resulted in poorer image quality as compared to a 5 Fr catheter (96% acceptable). Image quality for 5, 6, and 7 Fr sheath injections was 86%, 91%, 98%, respectively. The bench model of peripheral angiography demonstrated a significant reduction in reflux of contrast proximal to the end of the catheter without loss of antegrade image quality - confirming the in vivo findings. We demonstrate that the use of the AVERT device during peripheral angiography results in significant contrast savings without compromising image quality.

Balanced homodyne detection with high common mode rejection ratio based on parameter compensation of two arbitrary photodiodes.

A balanced homodyne detector, with a maximum common mode rejection ratio and clearance of 75.2 dB and 37 dB, is experimentally obtained with two arbitrary photodiodes of the same model. On the basis of self-subtraction photodetector scheme, we divide the influence of photodiodes on the common mode rejection ratio into two parts, including magnitude and phase of output signal. The discrepancy of quantum efficiency and dark current affects magnitude of output signal of photodiodes, which is compensated by adjusting the splitter ratio. The difference of the equivalent capacitance and resistance affects the phase of output signal of photodiodes, which is compensated by the differential fine tuning circuit and adjustable bias voltage circuit. With these designs, the developed homodyne detector can be used for measuring accurately the squeezed state.

Clock and Synchronization Networks for a 3 GHz 64 Bit ARMv8 8-Core SoC

This paper describes the clock distribution and synchronization network for a 64 bit ARMv8 8-core microprocessor. Embedded in a SoC for cloud computing platforms, the processor is fabricated in a 40 nm CMOS technology and operates at 3.0 GHz. The system PLL has a measured rms jitter <;1 ps and features dynamic frequency hopping for DVFS applications. In conjunction with a Star/H/Mesh topology, the clock distribution uses both CML and CMOS circuits to minimize period jitter and nominally achieves <;0.8 ps/mV | rms and <;9 ps of period jitter and skew, respectively. By using local Duty Cycle Adjustment circuits in each core to properly offset the clock duty cycle and ease timing critical paths, the processor performance improves by more than 5%. A simple probing circuit for high speed clock measurements can be used to monitor the high frequency excursions of the internal supply to counteract any timing violation that could occur. Finally an enhanced latch, which improves MTBF by up to 5 orders of magnitude and thus is suited for high speed synchronization operations, is proposed.

Simple synthetic protein scaffolds can create adjustable artificial MAPK circuits in yeast and mammalian cells.

As hubs for eukaryotic cell signaling, scaffold proteins are attractive targets for engineering and manipulating signaling circuits. We designed synthetic scaffolds with a repeated PDZ domain that interacted with engineered kinases of the mitogen-activated protein kinase (MAPK) cascade involved in yeast mating to investigate how modular interactions mediate kinase cascades. The synthetic scaffolds functioned as logic gates of signaling circuits. We replaced the endogenous yeast scaffold Ste5 with designer scaffolds with a variable numbers of a PDZ domain that bound kinases or phosphatases engineered with a PDZ-binding motif. Although association with the membrane was necessary for pathway activity, surprisingly, mating responses occurred when the circuit contained a scaffold with only two PDZ domains, which could only bind two of the three kinases simultaneously. Additionally, the three tiers of the MAPK pathway exhibited decreasing positional plasticity from the top [MAPK kinase kinase (MAPKKK)] to the bottom (MAPK) tier such that binding of a MAPKKK, but not a MAPK, from the osmoregulatory pathway or protein kinase C pathway to the synthetic scaffold activated a reporter of the mating response. We also showed that the output duration and intensity could be altered by recruiting phosphatases or varying the affinity of the recruited proteins for the scaffold and that a designer MAPK scaffold functioned in mammalian cells. Thus, this synthetic approach with designer scaffolds should enable the rational manipulation or engineering of signaling pathways and provide insight into the functional roles of scaffold proteins.

Design of a 1.12 Gb/s 11.3 mW low-voltage differential signaling transmitter**Project supported by the National Science and Technology Support Program of China (No. 2012BAI13B07) and the National High-Tech Research and Development Program of China (No. 2013AA014101).

This paper presents a 1.12 Gb/s 11.3 mW transmitter using 0.18 μm mixed signal complementary metal-oxide semiconductor technology with a 1.8 V supply voltage. This transmitter implements a high-speed transmission with 1.2 V common-mode output voltage, adopting a low-voltage differential signaling (LVDS) technique. A multiplexer (MUX) and an LVDS driver are critical for a transmitter to complete a high-speed data transmission. This paper proposes a high power-efficiency single-stage 14 : 1 MUX and an adjustable LVDS driver circuit, capable of driving different loads with a slight increase in power consumption. The prototype chip implements a transmitter with a core area of 970 × 560 μm2, demonstrating low power consumption and adjustable driving capability.

Progress in the Reduction of Inductance in Three Kinds of High Voltage Energy Storage Capacitors

Today an energy storage capacitor having a lower equivalent series inductance (ESL) coupled with an improved terminal for better integration with the gas switch, will contribute to faster discharge times and lower driving impedance, making fast linear transformer driver more sensible and energy efficient. The ESL is an important parameter in the design and operation of pulsed power system and is sometimes difficult to obtain. A ringing discharge method and a differential method to measure, simply and accurately, the ESL of three different kinds of high voltage energy storage capacitors are described in this paper. An error analysis of the differential method is also discussed. The ringing discharge method requires the capacitor tested to be fitted with an adjustable external short circuit and spark gap, while the differential method measures the ESL over a wide range of inductance, including extremely low inductance values, without specialized equipment or intricate data interpretation. These work and results can give some advices to design or optimize linear transformer driver.

Characterization of a Traffic Management System Using Pyroelectric Infrared Sensors

The hardware and software is described for a traffic flow system based on infrared sensors. Ultrasonic ranging and the infrared sensor-based speed measurement programs are compared. The selection of infrared sensors and the application of a Fresnel lens are described. A pyroelectric sensor is used in the infrared detection system to monitor vehicle information and convert it into an electrical signal. Using an amplifier circuit and a window comparator, external interrupt signals of a microcontroller are triggered to characterize traffic-flow and vehicle velocity. The system has adjustable sensitivity and a simple design and includes automatic threshold adjustment circuit, an adjustment scheme for a digital potentiometer, and an interrupt function program. In addition, the traffic-flow and vehicle-velocity are displayed. An application of the system is reported.

Microwave heating device for internal heating convection experiments, applied to Earth's mantle dynamics.

We report the design, construction, and performances of a microwave (MW) heating device for laboratory experiments with non-contact, homogeneous internal heating. The device generates MW radiation at 2.47 GHz from a commercial magnetron supplied by a pulsed current inverter using proprietary, feedback based command and control hardware and software. Specially designed MW launchers direct the MW radiation into the sample through a MW homogenizer, devised to even the MW power distribution into the sample's volume. An adjustable MW circuit adapts the MW generator to the load (i.e., the sample) placed in the experiment chamber. Dedicated heatsinks maintain the MW circuits at constant temperature throughout the experiment. Openings for laser scanning for image acquisition with a CCD camera and for the cooling circuits are protected by special MW filters. The performances of the device are analyzed in terms of heating uniformity, long term output power stability, and load matching. The device is used for small scale experiments simulating Earth's mantle convection. The 30 × 30 × 5 cm(3) convection tank is filled with a water‑based viscous fluid. A uniform and constant temperature is maintained at the upper boundary by an aluminum heat exchanger and adiabatic conditions apply at the tank base. We characterize the geometry of the convective regime as well as its bulk thermal evolution by measuring the velocity field by Particle Image Velocimetry and the temperature field by using Thermochromic Liquid Crystals.

A 1.1nW Energy Harvesting System with 544pW Quiescent Power for Next Generation Implants.

This paper presents a nW power management unit (PMU) for an autonomous wireless sensor that sustains itself by harvesting energy from the endocochlear potential (EP), the 70-100 mV electrochemical bio-potential inside the mammalian ear. Due to the anatomical constraints inside the inner ear, the total extractable power from the EP is limited to 1.1-6.25 nW. A nW boost converter is used to increase the input voltage (30-55 mV) to a higher voltage (0.8 to 1.1 V) usable by CMOS circuits in the sensor. A pW Charge Pump circuit is used to minimize the leakage in the boost converter. Further, ultra-low-power control circuits consisting of digital implementations of input impedance adjustment circuits and Zero Current Switching circuits along with Timer and Reference circuits keep the quiescent power of the PMU down to 544 pW. The designed boost converter achieves a peak power conversion efficiency of 56%. The PMU can sustain itself and a duty-cyled ultra-low power load while extracting power from the EP of a live guinea pig. The PMU circuits have been implemented on a 0.18µm CMOS process.

A magnetic induction heating system with multi-cascaded coils and adjustable magnetic circuit for hyperthermia

Based on the characteristics of cancer cells that cannot survive in an environment with temperature over 42 °C, a magnetic induction heating system for cancer treatment is developed in this work. First, the methods and analyses for designing the multi-cascaded coils magnetic induction hyperthermia system are proposed, such as internal impedance measurement of power generator, impedance matching of coils, and analysis of the system. Besides, characteristics of the system are simulated by a full-wave package for engineering optimization. Furthermore, by considering the safety factor of patients, a two-sectional needle is designed for hyperthermia. Finally, this system is employed to test the liver of swine in ex-vivo experiments, and through Hematoxylin and Eosin (H&E) stain and NADPH oxidase activity assay, the feasibility of this system is verified.

Design Techniques for a Mixed-Signal I/Q 32-Coefficient Rx-Feedforward Equalizer, 100-Coefficient Decision Feedback Equalizer in an 8 Gb/s 60 GHz 65 nm LP CMOS Receiver

This paper describes a mixed-signal I/Q 32-coefficient receive-side feedforward equalizer (RX-FFE) and 100-coefficient decision feedback equalizer (DFE) for a 60 GHz baseband. Integrated in 65 nm LP CMOS with variable gain amplifiers (VGA), analog phase rotator (PR), and clock generation and phase adjustment circuits, the I/Q equalizer supports 60 GHz WiGig non-line-of-sight (NLOS) channels with > 12 ns of delay spread while consuming 66 mW from a 1.2 V supply at 8 Gb/s. Energy-efficient equalization is achieved by the RX-FFE using a proposed switching matrix architecture, and by implementing the multi-coefficient FFE-DFE summing with cascoded current integration.

A solar‐powered 2.4‐GHz CMOS VCO

ABSTRACTA solar‐powered 2.4‐GHz voltage‐controlled oscillator (VCO) is developed using an energy harvesting technique. The main feature of the VCO is self‐powered by a solar panel with an adjustable voltage regulator circuit which directly converts solar power to the electrical power. The presented VCO design is based on an NMOS‐only cross‐coupled pair with an integrated LC tank. The capacitor and varactor in this LC tank are the intrinsic junction capacitors of NMOS transistors. The VCO is implemented using the TSMC 0.18 µm CMOS standard process. Measurements of the solar‐powered VCO are made, revealing that the output power is −17.46 dBm; the phase noise is −116.87 dBc/Hz at a 1 MHz offset, and the frequency tuning range is 3.4 %. The supply voltage that is applied to VCO is only 0.5 V with a power consumption of 1.25 mW. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2874–2878, 2014

Development of a high-density position decoder circuit for GAPD-based PET with a large number of readout channels

Channel reduction techniques are useful for reducing the number of channels being digitized and for constructing cost effective DAQ systems. The purpose of this study was to develop a channel reduction circuit which could be used to identify the interacted channel with a coincidence event from the 256 signals transferred from PET detectors. The channel reduction circuit would then output a channel address and analog pulse corresponding to the valid channel. The circuit, called a “position decoder circuit (PDC)”, consisted of a 256 channel gain adjust circuit, eight 32:1 PDCs, and one 8:1 PDC. Two PDC boards were constructed to evaluate the performance and usefulness of the developed PDC for PET applications. The proof-of-principle PET detector block composed of a 4×4 matrix of detector modules, each of which consisted of a LYSO scintillator coupled to a 4×4 array GAPD, was also constructed. A valid channel was successfully identified by the developed PDC, and the channel address and analog pulse outputs of the interacted channel were accurately measured. The variation of the gains for all detector channels was decreased by about 78% using the gain adjustment circuit implemented in the PDC. Moreover, average energy resolution was improved by approximately 8%. The discrepancy of timing resolutions acquired with and without the PDC was negligibly small. Single/coincidence count rates were 209.3/3.2cps with the PDC and 232.7/3.8cps without the PDC. Tomographic image of the hot-rod phantom was successfully acquired using the PDC. Experimental results indicate that the PDC is useful to identify a valid channel among a large number of readout channels of PET detectors. The results also indicate that the PDC is feasible to provide high-quality PET image.

A DISTINCTIVE METHOD OF ELIMINATING OUT-BAND INSTABILITY IN CASCADED ACTIVE DEVICE SYSTEM BASED ON NARROW-BAND ATTENUATION

A distinctive connection method in cascaded RF/MW active device system achieving both stability and low gain loss is presented. Unlike traditional methods (isolator and attenuator), the proposed solution introduces an appropriate length of transmission line to change the input impedance at the out-band instable frequency point and uses a narrow-band termination to absorb the instable power without deteriorating in-band signal. Moreover, the reason that instability often occurs in the cascaded system is analysed with S-parameters, and it turns out to be a kind of out-band instability. The solution is verified by an adjustable circuit example whose insertion loss is below 0.3 dB.

A 0.7–2.7-GHz Blocker-Tolerant Compact-Size Single-Antenna Receiver for Wideband Mobile Applications

Passive-mixer-first receivers have recently demonstrated flexible, low-noise, and high-linearity performance. Likewise, capacitive coupling element antennas have been demonstrated to be a viable choice for mobile handset integration. This paper combines these two advances into a single-antenna wideband receiver that achieves a 0.7-2.7-GHz reception band. The compact-size wideband tunable antenna achieves an efficiency of 45%-69% and occupies a volume of 2500 mm3. The front-end integrated circuit achieves an input compression point of +5 dBm with a noise figure of 4 dB while occupying only 0.3 mm2 of active die area. Additionally, an interface impedance study is performed to find the optimal impedances around the passive mixer and to demonstrate the different design tradeoffs of a passive-mixer-first receiver. A local oscillator duty-cycle adjustment circuit and its effect on the receiver performance is also presented.

A Novel Integrated Angle Measurement System

A novel integrated angle measurement system is proposed, which is based on CAN bus and can solve the problem that the traditional shaft angle measurement device is sensitive to disturbances and lack of network interface. The hardware circuits are designed based on the digital signal processor (DSP) TMS320F2812 and the resolver-to-digital converter (RDC) AD2S83. In addition, an adjustable frequency circuit based on Direct Digital Synthesizer (DDS) is designed to provide a precise reference signal. The software design is also introduced. The experimental results show that the angle measurement system is reliable, high accuracy, compact and convenient to be used.

Impact of NBTI-Induced Pulse-Width Modulation on SET Pulse-Width Measurement

This paper gives an explanation that SET pulse-width modulation in bulk CMOS devices happens due to negative bias temperature instability (NBTI). To investigate this, we propose and implement a stress adjustable pulse-width measurement circuit. Measurement results of test chips fabricated in a 65nm bulk CMOS process clearly show that pulse-width broadening and shrinking depend on the condition of static and dynamic stress before the pulse propagation. The measured dependency of pulse-width modulation on supply voltage is well correlated with that of NBTI model. We also point out that soft error rate computed from SET pulse-width distribution measured under static stress is pessimistic.

Design of Collection and Conditioning Circuit for a High Precision System of Photoelectric Velocity Measurement

In order to meet the requirements of high-speed projectile velocity measurement, design of a high-precision projectile velocity measurement device. Device adopts laser light source as detection target surface, receiving part adopts silicon cell array for photoelectric conversion. Silicon cell array using seamless splicing technology, eliminate the test blind spot. Design the sensitivity adjustable photoelectric conversion circuit, can effectively adjust the sensitivity of each pixel of the silicon photocell, effectively resolve the pixels sensitivity difference, reduce the jump poor in test, improve the projectile velocity measurement precision.

The Detection System of Adaptive Electrochemical Micro Electric Current

The existing micro current detecting apparatus is of large size and is manual controlled. When the detected currents sensitivity is higher, however, stability will be worse. In order to solve this problem, an adaptive detection system is proposed in this paper. The system designed a micro current signal detection circuit based on OK6410 embedded with development board. The Weak current signal is collected with the high precision ADC. Automatic adjustment circuit gain is from 1 to 10000. Spectrometer wavelength size is changed in real-time. Current resolution can reach nA. The experimental results show that this system can collect the micro current effectively. The main characteristics of the system are simple circuit structure, small volume, high degree of automation, and strong reliability, and it greatly improves the anti-interference performance of the circuit. The system can not only be applied in electrochemical current detection, but also be widely used in weak signal detection.