Circuit Description Research Articles

Wu’s Characteristic Set Method for SystemVerilog Assertions Verification

We propose a verification solution based on characteristic set of Wu’s method towards SystemVerilog assertion checking over digital circuit systems. We define a suitable subset of SVAs so that an efficient polynomial modeling mechanism for both circuit descriptions and assertions can be applied. We present an algorithm framework based on the algebraic representations using characteristic set of polynomial system. This symbolic algebraic approach is a useful supplement to the existent verification methods based on simulation.

An Active-Only Temperature-Insensitive Current-Mode Biquad Filter Based on Differentiator Structures Employing CCCCTAs

This article presents an active-only current-mode universal biquad filter performing three standard functions: low-pass, high-pass and band-pass function, which can be readily modified to achieve the rest functions (band-stop and all-pass). The circuit principle is based on active-only circuit designed by using differentiators which are constructed from current controlled current conveyor transconductance amplifier (CCCCTA) cooperating with an internally frequency compensated operational amplifier (OA). The features of the circuit are that: the pole frequency and quality factor can be independently tuned via the input bias currents and it is ideally temperature-insensitive, its circuit description is very simple, consisting of 3 CCCCTAs and 2 operational amplifiers, and the proposed circuit is very appropriate for further developing into integrated circuit architecture. The PSpice simulation results are shown. The given results agree well with the theoretical anticipation.

Telemetry Systems

Telemetry Systems

A Synthesis of Electronically Controllable Current-Mode PI, PD and PID Controllers Employing CCCDBAs

This paper presents a synthesis of current-mode PI, PD and PID controllers employing current controlled current differential buffer amplifiers (CCCDBAs). The features of these controllers are that: the output parameters can be electronically/independently controlled by adjusting corresponding bias currents in the proportional, integral, and deviation controllers; circuit description of the PID controller is simply formulated, it consists of four CCCDBAs cooperating with two grounded capacitors, and PI and PD controllers are composed of three CCCCDBAs and a grounded capacitor. Without any external resistor, the proposed circuits are very suitable to develop into integrated circuit architecture. The given results from the PSpice simulation agree well with the theoretical anticipation. The approximate power consumption in a closed loop control system consisting of the PI, PD and PID controller with low-pass filter passive plant are 4.03 mW, 4.85 mW and 5.71 mW, respectively, at ±1.5 V power supply voltages.

Elucidating Capacitance and Resistance Terms in Confined Electroactive Molecular Layers

Electrochemical analyses on confined electroactive molecular layers, herein exemplified with electroactive self-assembled monolayers, sample current contributions that are significantly influenced by additional nonfaradaic and uncompensated resistance effects that, though unresolved, can strongly distort redox analysis. Prior work has shown that impedance-derived capacitance spectroscopy approaches can cleanly resolve all contributions generated at such films, including those which are related to the layer dipolar/electrostatic relaxation characteristics. We show herein that, in isolating the faradaic and nonfaradaic contributions present within an improved equivalent circuit description of such interfaces, it is possible to accurately simulate subsequently observed cyclic voltammograms (that is, generated current versus potential patterns map accurately onto frequency domain measurements). Not only does this enable a frequency-resolved quantification of all components present, and in so doing, a full validation of the equivalent circuit model utilized, but also facilitates the generation of background subtracted cyclic voltammograms remarkably free from all but faradaic contributions.

Specification of photonic circuits using quantum hardware description language

Following the simple observation that the interconnection of a set of quantum optical input–output devices can be specified using structural mode VHSIC hardware description language, we demonstrate a computer-aided schematic capture workflow for modelling and simulating multi-component photonic circuits. We describe an algorithm for parsing circuit descriptions to derive quantum equations of motion, illustrate our approach using simple examples based on linear and cavity-nonlinear optical components, and demonstrate a computational approach to hierarchical model reduction.

Quantum description of a time-dependent mesoscopic RLC circuit

In this paper, we present a comprehensive quantum description of a mesoscopic RLC circuit with time-dependent resistance, inductance and capacitance. Based on the dynamical invariant method and using quadratic invariants, we derive exact nonstationary quantum states for this circuit and write them in terms of solutions of the Milne–Pinney equation. Afterwards, we use quadratic invariants to construct coherent states for this quantized system and employ them to investigate quantum properties of the RLC circuit. In particular, we show that the product of the quantum fluctuations of the charge and the magnetic flux does not satisfy the minimum uncertainty relation.

Versatile Linear and Digital Optocouplers to Reduce Noise and Ground Loop Errors in Measurements

The paper describes design details of low-cost, versatile, linear as well as digital optocoupler circuits used to reduce noise and ground loop errors in measurements. A detailed description of a linear optocoupler circuit for providing galvanic isolation between photodiode signal conditioner ground and the data logger ground is given. We also report use of two single-channel high-speed digital optocouplers to communicate through RS232 protocol isolating the ground of the devices in the detection region of the Cs fountain frequency standard being developed at NPL India. These isolators are versatile, affordable, and give very good results.

Invited Review Article: Physics and Monte Carlo techniques as relevant to cryogenic, phonon, and ionization readout of Cryogenic Dark Matter Search radiation detectors

This review discusses detector physics and Monte Carlo techniques for cryogenic, radiation detectors that utilize combined phonon and ionization readout. A general review of cryogenic phonon and charge transport is provided along with specific details of the Cryogenic Dark Matter Search detector instrumentation. In particular, this review covers quasidiffusive phonon transport, which includes phonon focusing, anharmonic decay, and isotope scattering. The interaction of phonons in the detector surface is discussed along with the downconversion of phonons in superconducting films. The charge transport physics include a mass tensor which results from the crystal band structure and is modeled with a Herring-Vogt transformation. Charge scattering processes involve the creation of Neganov-Luke phonons. Transition-edge-sensor (TES) simulations include a full electric circuit description and all thermal processes including Joule heating, cooling to the substrate, and thermal diffusion within the TES, the latter of which is necessary to model normal-superconducting phase separation. Relevant numerical constants are provided for these physical processes in germanium, silicon, aluminum, and tungsten. Random number sampling methods including inverse cumulative distribution function (CDF) and rejection techniques are reviewed. To improve the efficiency of charge transport modeling, an additional second order inverse CDF method is developed here along with an efficient barycentric coordinate sampling method of electric fields. Results are provided in a manner that is convenient for use in Monte Carlo and references are provided for validation of these models.

Two action systems in the human brain

The distinction between dorsal and ventral visual processing streams, first proposed by Ungerleider and Mishkin (1982) and later refined by Milner and Goodale (1995) has been elaborated substantially in recent years, spurred by two developments. The first was proposed in large part by Rizzolatti and Matelli (2003) and is a more detailed description of the multiple neural circuits connecting the frontal, temporal, and parietal cortices. Secondly, there are a number of behavioral observations that the classic “two visual systems” hypothesis is unable to accommodate without additional assumptions. The notion that the Dorsal stream is specialized for “where” or “how” actions and the Ventral stream for “What” knowledge cannot account for two prominent disorders of action, limb apraxia and optic ataxia, that represent a double dissociation in terms of the types of actions that are preserved and impaired. A growing body of evidence, instead, suggests that there are at least two distinct Dorsal routes in the human brain, referred to as the “Grasp” and “Use” systems. Both of these may be differentiated from the Ventral route in terms of neuroanatomic localization, representational specificity, and time course of information processing.

A Multichannel Magnetic Flux Controller for Periodic Magnetizing Conditions

International standards for testing soft magnetic materials require that the magnetic flux density remain sinusoidal with respect to time. Traditionally, this has been achieved via control of the magnetic flux using either analog feedback, which provides real-time control, or iterative digital feedback, which yields more accurate solutions with the cost of increased convergence time. In certain applications, such as magnetic nondestructive testing, rapid convergence of multiple interacting flux controlled channels is required. In this paper, a multichannel flux controller design is presented that combines the real-time performance of analog feedback with an iterative digital feedback algorithm to reduce error. The system demonstrates a 95% reduction in convergence time at power line frequencies over a comparable system using only digital feedback. Several examples of the system's ability to control arbitrary periodic waveforms are presented over the frequency range from 0.735 Hz to 100 Hz. Sinusoidal form factor errors are shown to be 0.1% from 2 Hz to 100 Hz across four strongly coupled channels with highly nonlinear magnetizing conditions. A detailed description of both analog circuit and digital algorithms is provided.

Tunable broad-band perfect absorber by exciting of multiple plasmon resonances at optical frequency

A broad-band perfect absorber composing a two-dimensional periodic metal-dielectric-metal sandwiches array on dielectric/metal substrate is designed and numerically investigated. It is shown that the nearly-perfect absorption with a bandwidth of about 50 nm in visible region can be achieved by overlapping of two plasmon resonances: one originating from the coupling of electric dipoles between adjacent unit cells and another arising from magnetic dipole plasmon resonances. A capacitor-inductor circuit description is introduced to explain the dependence of resonance frequencies and band-width on geometrical parameters.

Deterministic and Stochastic Descriptions of Gene Expression Dynamics

A key goal of systems biology is the predictive mathematical description of gene regulatory circuits. Different approaches are used such as deterministic and stochastic models, models that describe cell growth and division explicitly or implicitly etc. Here we consider simple systems of unregulated (constitutive) gene expression and compare different mathematical descriptions systematically to obtain insight into the errors that are introduced by various common approximations such as describing cell growth and division by an effective protein degradation term. In particular, we show that the population average of protein content of a cell exhibits a subtle dependence on the dynamics of growth and division, the specific model for volume growth and the age structure of the population. Nevertheless, the error made by models with implicit cell growth and division is quite small. Furthermore, we compare various models that are partially stochastic to investigate the impact of different sources of (intrinsic) noise. This comparison indicates that different sources of noise (protein synthesis, partitioning in cell division) contribute comparable amounts of noise if protein synthesis is not or only weakly bursty. If protein synthesis is very bursty, the burstiness is the dominant noise source, independent of other details of the model. Finally, we discuss two sources of extrinsic noise: cell-to-cell variations in protein content due to cells being at different stages in the division cycles, which we show to be small (for the protein concentration and, surprisingly, also for the protein copy number per cell) and fluctuations in the growth rate, which can have a significant impact.

A Formal Approach to Designing Cryptographic Processors Based on $GF(2^m)$ Arithmetic Circuits

This paper proposes a formal approach to designing Galois-field (GF) arithmetic circuits, which are widely used in modern cryptographic processors. Our method describes GF arithmetic circuits in a hierarchical manner with high-level directed graphs associated with specific GFs and arithmetic functions. The proposed circuit description can be effectively verified by symbolic computations based on polynomial reduction using Grobner bases. The verified description is then translated into the equivalent hardware description language (HDL) codes, which are available for the conventional design flow. We first describe the proposed graph representation and present an example of the description and verification. The significant advantage of the proposed approach is demonstrated through experimental designs of parallel multipliers over GF(2m) for different word lengths and irreducible polynomials. The result shows that the proposed approach has a definite capability of formally verifying practical GF arithmetic circuits for which the conventional techniques fail. We also propose an application of this approach to cryptographic processor design. The target considered here is a 128-bit advanced encryption standard (AES) data path with a loop architecture. To the best of the authors' knowledge, this is the first verification of this type of practical AES data path. We present a detailed description of the AES data path and its verification. The proposed approach successfully verifies the AES data path description within 800 s.

Transient and Permanent Fault Injection in VHDL Description of Digital Circuits

The ability to evaluate the testability of digital circuits before they are actually implemented is critical for designing highly reliable systems. This feature enables designers to verify the fault detection capability of online as well as offline testable digital circuits for both permanent and transient faults, during the design stage of the circuits. This paper presents a technique for transient and permanent fault injection at the VHDL level description of both combinational and sequential digital circuits. Access to all VHDL blocks a system is straight forward using a specially designed single fault injection block. This capability of inserting transient and permanent faults should help in evaluating the testability of a digital system before it is actually implemented.

Memristive port-Hamiltonian control: path-dependent damping injection in control of mechanical systems

This paper presents the use of the memristor as a new element for designing passivity-based controllers. From the port-Hamiltonian description of the electrical circuits with memristors, a target dynamics is assigned to the matching equation proposed by the methodology known as Interconnection and Damping Assignment-Passivity-based Control. The inclusion of the memristor element extends the closed loop dynamics and it results in an extra term in the control algorithm that can be seen as a state-modulated gain. Two mechanical examples, in the form of a position control systems are included to show possible applications.

Hamiltonian modeling of generator integrated AVR and PSS

In this article AVR and PSS are integrated with generator, and constituted the complete object-oriented model included generator and its controllers. By means of energy composition of analog circuit, controller AVR and PSS equivalent energy function descriptions are obtained. Then controller energy functions are added to the generator Hamiltonian function, and composed the total energy function of system. Furthermore, a Hamiltonian model of generator integrated AVR and PSS is derived. Finally, according to the dissipative properties of Hamiltonian model, AVR and PSS influences on generator system dissipative properties are analyzed, and PSS damping effect on port is discussed. The results show that damping characteristics reflected in the model are consistent with practical system.

Lagrangian and Hamiltonian Formulations for Classical and Quantum Circuits

AbstractThe application of Lagrange and Hamilton methods to classical electric circuits and to circuit quantum electrodynamic circuits is presented. The formulation of the Lagrangian and Hamiltonian equations for lossless electric circuits including linear and nonlinear circuit elements is discussed. The considered circuits are subdivided into a linear embedding circuit and the embedded nonlinear circuit elements. The embedding circuits are represented as a Lagrangian or Hamiltonian system with port variables. On the basis of the of the classical Hamiltonian description of circuits a circuit quantum electrodynamic representation is introduced. As examples for classical and quantum circuits, Josephson circuits are discussed.

Resolution of Diagnosis Based on Transition Faults

The conventional detection conditions for transition faults do not predict fault effects that may be created when transition faults are activated and/or propagated by pulses (or hazards). For this, detection conditions that take hazards into consideration need to be used. However, since the occurrence of pulses cannot be predicted accurately based on a gate-level circuit description, the transition fault model becomes more susceptible to pattern-dependent effects, where errors on observed outputs that are predicted by the fault model may not appear in a circuit-under-diagnosis. This paper considers the implications of these pattern-dependent effects on the resolution of fault diagnosis based on transition faults.

Nonlinear spectroscopy of superconducting anharmonic resonators

We formulate a model for the steady state response of a nonlinear quantum oscillator structure, such as those used in a variety of superconducting qubit experiments, when excited by a steady, but not necessarily small, ac tone. We show that this model can be derived directly from a circuit description of some recent qubit experiments in which the state of the qubit is read out directly, without a superconducting quantum interference device (SQUID) magnetometer. The excitation profile has a rich structure depending on the detuning of the tone from the small-signal resonant frequency, on the degree of damping and on the excitation amplitude. We explore two regions in detail. Firstly, at high damping there is a trough in the excitation response as a function of detuning, near where the classical Duffing bifurcation occurs. This trough has been understood as a classical interference between two metastable responses with opposite phase. We use Wigner function studies to show that while this picture is roughly correct, there are also more quantum mechanical aspects to this feature. Secondly, at low damping we study the emergence of sharp, discrete spectral features from a continuum response. We show that these the structures, associated with discrete transitions between different excited-state eigenstates of the oscillator, provide an interesting example of a quantum Fano resonance. The trough in the Fano response evolves continuously from the ‘classical’ trough at high damping.