Circuit Design Problems Research Articles

Applied optimization and circuit design

A qualitative review of applied optimization forms is given, illustrated by reference to the linear circuit design problem. When used to solve very difficult problems, optimization theory becomes extremely vague with many conflicting objectives. These opposing standpoints are discussed and an approach is described which attempts to handle the complications. Working online, many of these nebulous aspects can be considered at run-time. To illustrate this approach a lumped-element simulation of a coaxial cable over a frequency band of 1 2 MHz-1 GHz is described.

Modeling of an ion-implanted silicon-gate depletion-mode IGFET

A dc model is-presented for the ion-implemented silicon-gate depletion-mode IGFET from which the device terminal behavior can be determined. The device equations are derived based on the concept of a finite semiconductor capacitance in the channel region whereby the depth of the implanted channel is taken into account. The model parameter is shown to be easily measurable experimentally. The validity of the resulting model is demonstrated by showing good agreement between calculated and measured results obtained from fabricated devices, It is believed that this model lends itself well to the circuit design problem using depletion mode IGFET's.

DISOPT—A general programme for continuous and discrete non-linear programming problems†

Abstract An integrated computer programme in Fortran IV for continuous or discrete non linear programming problems is presented. Several recent techniques and algorithms for non-linear programming have been adapted and new ideas have been introduced. They include the minimax and exterior-point approaches to non-linear programming, least pth optimization and the Dakin tree-search algorithm. The user may optionally choose the combination of techniques and algorithms best suited to his problems. Since many practical design problems can be easily formulated as non-linear programming problems, the programme, called DISOPT, enjoys a very wide range of applications such as continuous and discrete tolerance assignments, digital filter design, circuit design, system modelling and approximation problems. Numerical results for a number of functions and circuit tolerance optimization problems are presented in this paper to demonstrate the performance of DISOPT.

Computers in eletronics design

The advent of interactive computer design systems has played a significant part in the design and development of printed-circuit boards and integrated circuits. Working as a team, the designer and the computer can optimise the solution to a given circuit-design problem

Circuit design by minimization using the Hessian matrix

The Hessian matrix of the objective function in the problem of circuit design by minimization can be determined explicitly and its use in a second-order minimization process is now feasible and is presented. The process begins with the steepest descent method, followed by a generalized Newton method. At each iteration, the incremental step as prescribed by the respective method is taken unless the function is locally increasing, in which case, the direction is reversed. If the function has increased at a trial point, a cubic interpolation between the current point and that point is performed and the next point is taken to be at the minimum of the cubic. To ensure that the cubic approximation is reasonable, the step size is controlled. Examples are given and the results are compared with those obtained by the gradient method of Fletcher and Powell.

Telecommunications Systems Modeling in the Laboratory

This paper describes a laboratory developed to accompany a course in communications theory. The laboratory program is based on the use of building block modules, corresponding to the standard elements found in communication systems. The use of such modules enables the students to model complete systems without becoming involved in detailed problems of circuit design. The module system is described and its use in typical experiments is discussed.

Computer Redundancy: Design, Performance, and Future

The literature on the theoretical aspects of redundancy in digital computers is extensive providing a sound basis for highly reliable design. This paper describes the design problems, the reliability prediction, the field performance, and the future application of redundancy techniques to digital systems. Triple modular redundancy (TMR) is described using the logic of the Launch Vehicle Digital Computer utilized in the uprated Saturn I and the Saturn V vehicles. The self-correcting memory of this computer is described along with the associated design problems and the design verification based on production experience. Consideration is given to system design problems involved with TMR logic. A Monte Carlo technique for predicting computer reliability is considered in a design engineering rather than programmer approach. The unique means of indicating single-channel malfunctions, while continuing to mask these single-channel malfunctions with respect to system operation, is introduced. The result of field operation are given and compared with predicted reliability. Quad redundancy at the component part level is described using the circuitry of the primary processor and data storage (PPDS) for NASA's Orbital Astronomical Observatory. The process of arriving at a quad redundancy implementation is considered in light of the constraints of cost, schedule, and an initial reliability requirement of 95 percent for a year's operation in space. The circuit and system design problems associated with quad redundancy such as impedance and part parameter variations, power consumption, fan out limitations, and testing restrictions are indicated. The results of field operation are given and compared with predicted reliability.

Computer-Aided Circuit Design by Singular Imbedding

We give a new and powerful method for the direct solution of circuit design problems. The method begins with a prespecified topology and some or all elements undetermined in value. The designer imposes on the circuit any desired set of node-pair voltages, branch currents, or driving point and transfer immittances. Values of circuit elements that satisfy the constraints are directly calculated. This direct method of solution avoids the usual iterative analysis-optimization schemes, reducing computer times by up to three orders of magnitude. A linear set of design equations is formulated by choosing undetermined element currents and node voltages as the variables. Singular elements are introduced to impose the desired constraints. Inequality as well as equality constraints are permitted. Element values are determined from the solution of these equations. In this paper we emphasize our method of solution in relation to dc networks.

Some Problems in Relay Circuit Design

In the design of sequential relay circuits one often has to consider the circuit as a part of a larger system, and one must take into account the nature of the inputs to the circuit. Frequently, the inputs are two-terminal contact networks with one terminal grounded; such inputs will be called simple. This paper examines the formal design techniques as applied to circuits with simple inputs. It is shown that all relays should be considered as secondary, from the point of view of both races and minimization. Several other shortcomings of the present theory are pointed out. Properties of circuits with simple inputs are examined. It is shown that there are flow tables not realizable without races with simple inputs, and that the presently known secondary assignment methods are not applicable to circuits with simple inputs.

Negative L and C in Solid-State Masers

The analysis of solid-state cavity masers is extended to include the reactive component of the paramagnetic resonance. This reactance is inverted (in opposition to Foster's reactance theorem). A two-cavity network makes use of this negative frequency dependence of reactance to obtain a broad-band flat-topped amplifier response. In verification of this theory a ruby maser has been built which has a 95-Mc bandwidth at 14-db gain and operates at 9000 Mc and 1.5°K. This performance is comparable to that of published, tapered magnetic field traveling-wave masers. General network limitations on cavity maser amplifiers are derived. Broadbanding techniques that have been published for parametric amplifiers are essentially equivalent. The tuning of the broad-band amplifier is critical. The same performance can be achieved in a unilateral transmission maser by using circularly polarized cavities, but the problem of circuit design and tuning with the increased number of parameters has thus far prevented successful operation.

A Computer Application to Reliable Circuit Design

The problem of reliable electronic circuit design by statistical methods is described. After a brief account of the history of this problem, we give the principle of one successful method-Monte Carlo. Two implementations of this method, as digital-computer programs, are given. The first program analyzes the reliability of a given circuit. The second program picks component values to optimize the circuit behavior with respect to several performance aspects. Examples illustrating the nature of the input and output information are included. ``... Civilization advances by extending the number of important operations which we can perform without thinking about them ....'' -A. N. Whitehead

Nuclear Protective System Design for Reliability

With respect to three developments (the widespread use of solid state components as active circuit elements, the acknowledgment that the electronic protective system problem was a switching circuit and logic design problem, and the desire to reduce the probability of reactor shutdown to instrument failures and introduce the two of three coincidence or majority decision concept) system design concepts for reliability enhancement are provided, and system building blocks for a practical realization of these concepts are presented. Although the ideas presented are pointed toward nuclear reactor protective systems, it is felt that the same approaches can be applied to general systems design. (P.C.H.)

Boolean Matrix Equations in Digital Circuit Design

A systematic digital computational method is given that involves the use of Boolean matrix equations for solving certain types of functional circuit design problems. Specifically, all sets of Boolean functions f1(A1, . . ., A1), . . ., fJ(A1, - . . ., A1) are found such that if circuits with these outputs are connected to a circuit that generates the known Boolean function F(f1, . . . , fJ, X1, . . ., XK), then the output will produce a given desired function E(A1, . . ., A1, X1, . . ., XK). Illustrative examples of the method are presented.

Further data on the design of Eccles-Jordan flip-flops

The design of a prototype Eccles-Jordan flip-flop as used in large-scale digital computers is discussed, stressing the role of component variability. A graphical design technique is given, which should prove helpful in other switching circuit design problems using a large number of identical direct-coupled circuits.

The Servo Problem as a Transmission Problem

The purpose of a servo is to reproduce a signal at a place or power level or form different from the original signal, but under its control. It is therefore a signal-transmitting system. It uses negative feedback to minimize noise and distortion, which the servo designer usually calls error. It uses mechanical and thermal circuit elements as well as electrical circuit elements, but the problems of circuit design are the same. The methods of Nyquist and Bode, which have proved so useful in the design of electrical feedback amplifiers, are equally useful in the design of servo systems. They encourage the determination of the significant constants of the system by experimental means involving steady-state amplitude measurements.

A Contribution to Cascade Theory

The theory of the flow past cascades or infinite series of aerofoils, regularly spaced, is of importance in connection with the design of turbo-blower blades, interference between propeller blade root sections, wind tunnel circuit design and kindred problems. The usual development of the theory involves some rather advanced applications of conformal representation which it is rather difficult to translate into numerical terms, and no general solution for an arbitrary form of aerofoil section is available.