Current Sensing Completion Detection in Single-Rail Asynchronous Systems

In this article, an alternative approach to detecting the computation completion of combinatorial blocks in asynchronous digital systems is presented. The proposed methodology is based on well-known phenomenon that occurs in digital systems fabricated in CMOS technology. Such logic circuits exhibit significantly higher current consumption during the signal transitions than in the idle state. Duration of these current peaks correlates very well with the actual computation time of the combinatorial block. Hence, this fact can be exploited for separation of the computation activity from static state. The paper presents fundamental background of addressed alternative completion detection and its implementation in single-rail encoded asynchronous systems, the proposed current sensing circuitry, achieved simulation results as well as the comparison to the state-of-the-art methods of completion detection. The presented method promises the enhancement of the performance of an asynchronous circuit, and under certain circumstances it also reduces the silicon area requirements of the completion detection block

The instrument suite of the European Spallation Source

An overview is provided of the 15 neutron beam instruments making up the initial instrument suite of the European Spallation Source (ESS), and being made available to the neutron user community. The ESS neutron source consists of a high-power accelerator and target station, providing a unique long-pulse time structure of slow neutrons. The design considerations behind the time structure, moderator geometry and instrument layout are presented. The 15-instrument suite consists of two small-angle instruments, two reflectometers, an imaging beamline, two single-crystal diffractometers; one for macromolecular crystallography and one for magnetism, two powder diffractometers, and an engineering diffractometer, as well as an array of five inelastic instruments comprising two chopper spectrometers, an inverse-geometry single-crystal excitations spectrometer, an instrument for vibrational spectroscopy and a high-resolution backscattering spectrometer. The conceptual design, performance and scientific drivers of each of these instruments are described. All of the instruments are designed to provide breakthrough new scientific capability, not currently available at existing facilities, building on the inherent strengths of the ESS long-pulse neutron source of high flux, flexible resolution and large bandwidth. Each of them is predicted to provide world-leading performance at an accelerator power of 2 MW. This technical capability translates into a very broad range of scientific capabilities. The composition of the instrument suite has been chosen to maximise the breadth and depth of the scientific impact o

Maximum Power Point Tracking Circuit for an Energy Harvester in 130 nm CMOS Technology

This paper presents design of a Maximum Power Point Tracking (MPPT) circuit and its functionality for tuning the maximum power transfer from an energy harvester (EH) unit. Simple and practical “Perturb and Observe” (P&O) algorithm is investigated and implemented. We describe the circuit functionality and the improvements that have been introduced to the original algorithm. The proposed MPPT design is divided into three main blocks. The output signal is being generated by the PWM or PFM block. The tracking speed has been enhanced by implementing a variable step size in the “Tracking Block”. Finally, the overall power consumption of the MPPT circuit itself is controlled by the “Power Management Block”, which manages delivering the clock signal to the rest of the circuit. The RTL code of the proposed MPPT has been created in Verilog, synthesized and placed-and-routed in a general purpose 130 nm CMOS technology

Design of CMOS readout frontend circuit for MEMS capacitive microphones

This paper deals with a frontend part of the readout circuit developed as an integrated circuit that after bonding together with a MEMS capacitive microphone (MCM) chip will be used in a noise dosimeter applicable in very noisy and harsh environment, e.g. mine. Therefore, the main attention has been paid to the high dynamic range, low offset and low noise of the developed readout interface as well as its low- power consumption feature. For conversion of the MCM’s capacitance variation into voltage, an approach based on the buffered input conversion stage biased by a voltage divider was used. The advantage of this approach is that the voltage divider formed by MOS transistors can be connected to the high-impedance node (i.e. the output of the MCM, in this case). The whole frontend part of the readout interface was designed in a standard 0.35mm CMOS technology. Finally, the achieved results are discussed and compared to other works

Towards automatic gain control low-power amplifier in 130 nm CMOS technology

The paper addresses the design of a bulk-driven variable gain amplifier (VGA) in 130 nm general purpose CMOS technology. The VGA is intended to be employed within a low-power automatic gain control (AGC) block, which requires an examination of possible gain setting approaches. The mentioned investigation as well as the evaluation and comparison of the obtained results are presented. The amplifier has been designed to work with the power supply voltage of only 0.6 V, which introduces a whole series of challenges and obstacles. However, it also eliminates one of the main problems associated with bulk-driven circuits - the latch-up effect

Digital Calibration of Operational Amplifiers and Influence of Calibration Circuitry

This paper presents the implementation of a digital calibration method for a variable-gain amplifier (VGA), where the amplifier input offset voltage is the calibration target. The whole system is implemented in 130 nm CMOS technology using the supply voltage of 600 mV. Firstly,fundamentals of calibration circuitry operation are described, followed by detailed explanation of the proposed implementation. Then, investigation of possible undesired effects of calibration circuitry on the amplifier characteristics is performed. The whole calibration system was verified through simulation for various temperatures using Cadence environment and BSIM3v3 transistor model version. The VGA was calibrated within the temperature range from -20°C to 60°C, in which standard deviation of the input offset voltage reaches less than 802 μV and mean value is at most 450 μV. Using the calibration, the standard deviation is reduced to 35% compared to the VGA without the calibration, while the change of mean value is rather negligible

Performance analysis of monolithically integrated depletion-/enhancement-mode InAlN/GaN heterostructure HEMT transistors

The paper addresses a top-down design flow of depletion-load digital inverter formed by monolithically integrated depletion-mode and enhancement-mode high electron mobility transistors (HEMTs) on common InAlN/GaN heterostructure grown on sapphire substrate. We describe the inverter design at transistor level using HSPICE models developed earlier. The inverter layout representation, which also defines the lithographic masks required for the fabrication process, is presented as well. The proposed mask set was designed taking into account the design-for-manufacturing approach. Furthermore, we evaluated measured properties and performance of the fabricated transistors and circuits and recalibrate the transistor models according to the latest measurements

Analysis of Binding Interactions of Ramipril and Quercetin on Human Serum Albumin: A Novel Method in Affinity Evaluation

The aim of this study was to analyze the binding interactions between a common antihypertensive drug (ramipril, R) and the widely distributed plant flavonoid quercetin (Q), in the presence of human serum albumin (HSA). From the observed fluorescence spectra of the (HSA + R) system we can assume that ramipril is also one of the Site 3 ligands—similar to fusidic acid—the binding of which has been proven by RTG crystallography. Our claim is supported by near-UV CD spectroscopy, microscale themophoresis and molecular modeling. The presence of R slightly inhibited the subsequent binding of Q to HSA and, on the contrary, the pre-incubation of HSA with Q caused a stronger binding of R, most likely due to allosteric interactions. At high concentrations, R is also able to displace Q from its binding site. The dissociation constant KD for the binding of R is more than hundredfold larger than for Q, which means that R is a very weak binder to HSA. The knowledge of qualitative and quantitative parameters of R, as well as the methods used in this study, are important for future research into HSA binding. This study shows the importance of implementing other methods for KD determination. Microscale thermophoresis has proved to be a novel, practical and accurate method for KD determination on HSA, especially in cases when fluorescence spectroscopy is unable to produce usable results