Statistical design centring for electrical circuits

The problem of maximising the manufacturing yield of electrical circuits is addressed. Within the constraint that the absolute component tolerances and the forms of their statistical distributions are fixed, a new design-centring procedure is developed and illustrated by example. It is directly applicable to the design of discrete circuits where fixed tolerances are often considered. The assumption of fixed tolerances also suggests its relevance (as yet untested) to the design of integrated circuits.     

Tools for the computer-aided design of multigigahertzsuperconducting digital circuits

The realization of large integrated circuits depends upon the application of computer-aided design (CAD) tools. This paper summarizes the results of a survey of CAD tools targeting superconducting digital electronics. Five categories of tools: circuit simulators, circuit optimizers, layout tools, inductance estimators, and logic simulators are discussed in detail. Within each category, a comparison of several currently available CAD tools is presented, and a tool which has been adapted for use or developed at the University of Rochester is discussed in greater detail. In addition, tools for timing analysis as well as integrated design environments that permit the effective data interchange among various tools and support libraries of design models are discussed. Future tools for timing optimization, automated logic synthesis, and automated layout synthesis are shown to be necessary for the design of superconducting circuits at the very large scale of integration (VLSI) level of integration. Trends regarding changes in the requirements for effective CAD tools are discussed, and expected improvements to existing tools and features of new tools currently under development are presented     

Sensitivity analysis in computer-aided design of linear circuits

An approximate linear relation is established between the transfer function of a linear network and the component deviations. This can reduce the time consumed by a Monte Carlo sensitivity analysis. Little work is involved in evaluating the relationship beyond that already required for a conventional transient analysis.     

Optimum design of nonlinear microwave circuits

This paper reports a direct optimization method of nonlinear circuits. The procedure consists in determining in the power space, a surface including all the extremum allowed powers at terminal ports of each nonlinear component of the circuit. According to the required nonlinear function, an appropriate choice of the tangent planes to this surface allows to calculate the optimum loads for the nonlinear components. This method optimizes the parameters of nonlinear devices without any constraint on the circuit. A small signal analysis is then taken in order to deduce the optimum performance of the nonlinear designed circuit. The realization of a single balanced diode mixer has shown good agreement between the calculated values and the experimental results     

FIRGEN: a computer-aided design system for high performance FIRfilter integrated circuits

The authors describe automatic architecture and floorplan generation techniques for integrated circuit fixed-coefficient FIR (finite impulse response) filters that can achieve high sample rates with compact layouts. These techniques have been implemented in a filter design system called FIRGEN that can automate the entire design from filter specifications to final chip layout. It can be retargeted to new cell libraries and place and route tools. Result on four chips designed with FIRGEN are presented. These achieve sample rates ranging from 25 MHz to 112 MHz     

DEMON-an optimal seeking computer program for the design of microwave circuits

A program for the design of generalized TEM microwave circuits has been written. The optimization process utilizes a simple but effective rationale called direct pattern search to reduce the error between a desired circuit objective and the current value of a chosen response. Lossy transmission line equations are utilized in the program for exactness. As an example of its utility a 2-4-GHz maximally flat magnitude microwave transistor amplifier is designed and fabricated.     

CAD techniques for microwave circuits

In little more than 10 years computer-aided design (CAD) of microwave circuits has moved from dumb terminals on mainframe computers to PCs, and now to powerful RISC workstations. Commercial CAD software now integrates the various stages of microwave circuit design: schematic capture, simulation and layout. This paper reviews the different CAD packages that are available for microwave circuit design. The basic principles employed in the modelling of microstrip circuits are introduced and the reasons for the extensive use of frequency-domain simulations are explored. The developments in nonlinear, electromagnetic and system-level simulation methods are described     

Man-computer graphics for computer-aided design

This paper reviews the history, concepts, state-of-the-art, and future directions of the use of man-computer graphics for computer-aided design. Computer-aided design is based on a real-time graphical dialogue between the man and the computer in which the man draws on a display by means of a "light pen" or other input device. The computer "understands" the picture, makes calculations based on it, and presents the results pictorially to the user for his approval or revision. This man-computer graphical conversation has been made possible by recent advances in the speed of the digital computer, time-sharing programming, computer-driven display technology, and graphical input devices. The light pen is the most commonly used graphical input device, but keyboards, joysticks, flat matrix arrays, and other devices are also used. The programming state-of-the-art is a limiting factor in the implementatation of graphical computer-aided design; much work remains to be done in systems programming, efficient time sharing, list structure concepts, file organization, and memory protection. A number of experimental equipment configurations in use in various laboratories are cited and the hardware state-of-the-art is reviewed. Several experimental and production applications of computer-aided design evolved in a large aircraft company are described and illustrated, by display photographs. These applications relate to structural analysis, dynamics, information retrieval, accounting, and numerical control tape preparation. For the future, advances are required in improved man-computer communication, techniques to permit the operation of displays at great distances from the central computer, and methods of inputting existing drawings into the computer in a meaningful form.     

GaAs HBT's for microwave integrated circuits

The status of the microwave GaAs heterojunction bipolar transistor (HBT) technology is reviewed. Microwave circuits for advanced military and commercial systems continue to increase their dependence on the performance, functionality, and cost of active components fabricated using solid-state technology. The performance advantages provided by GaAs HBT's, for several critical circuit applications, have stimulated a worldwide development activity. Progress in HBT device technology and microwave circuit applications has been extremely rapid because of the broad availability of III-V compound semiconductor epitaxial materials and prior experience with GaAs field-effect transistors (FET's) and monolithic microwave integrated circuits (MMIC's). The great flexibility of HBT's in microwave circuits makes them prime candidates for applications in complex multifunctional microwave/digital IC's in next-generation systems     

Practical microwave circuits for groove waveguides

Groove guides have been known for many years. No practical microwave circuits have yet been described although these types of transmission lines could be used in many cases. This paper discusses the physical realizability of some wide band designs such as matched load, directional coupler, hybrid coupler, bend and phase shifter. Both closed and open groove guides have been investigated. Optical type components seem to be inappropriate for groove guide transmission. The best way to design components for these guides is to adapt those of standard rectangular guides, which perturb only the Rf fields in the vicinity of the narrow walls and to optimize the dimensions of the groove structure as a function of the losses and the symmetry of the induced spurious modes.     

Statistical RTS model for digital circuits

In this work we study the variation in drain current of MOS transistors due to the capture and emission of electrons at interface states (traps), called random telegraph signal (RTS). Usually, RTS is studied in frequency domain. However, for digital circuits, it is more appropriate to use time-domain representations.The time-domain representation here proposed models the effect of RTS on I_ds as instantaneous Vt shifts. We introduce a statistical numerical approach for computing the total ΔVt of the transistor considering all the traps in the interface. The method analyses the effect of non-uniform charge densities along the channel. To show the applicability of the methodology to circuit analysis on the electrical level, the model is applied to characterize read and write instability failures caused by RTS on a 6T-SRAM cell.     

Modeling of quantum-well lasers for computer-aided analysis ofoptoelectronic integrated circuits

A two-port circuit model for quantum-well (QW) lasers has been developed from rate equations. With emphasis on the physical principles, the phenomena of the recombination process of electron-hole pairs and the light wave resonance in the active region have been incorporated into this new model. The model has been implemented in a circuit simulator and validated with measured DC and transient laser characteristics. The frequency effects on the modulation properties of QW lasers have been studied and analyzed using a small-signal model. Simulation results show excellent agreement with experimental data     

Piezoelectric-transducer-controlled tunable microwave circuits

This paper introduces a new method to tune microwave circuits of phase shifters, filters, resonators, and oscillators, controlled by a piezoelectric transducer (PET) with computational and experimental results. An optimized PET-controlled phase shifter is demonstrated to operate up to 40 GHz with a maximum total loss of 4 dB and phase shift of 480°. PET-controlled tunable bandpass filter, ring resonator, and one-dimensional photonic-bandgap resonator show a very wide tuning bandwidth of 17.5%-28.5% near 10 GHz with little performance degradation. A new PET-controlled or voltage-controlled dielectric-resonator oscillator (DRO) is demonstrated with a tuning bandwidth of 3.7% at the center frequency of 11.78 GHz. The tuning bandwidth is slightly less than that of a mechanical tuning using a micrometer-head-controlled tunable DRO with a tuning bandwidth of 4.7%. The new tuning method should have many applications in monolithic and hybrid microwave integrated circuits     

GaAs integrated microwave circuits

GaAs has many desirable features that make it most useful for microwave and millimeter-wave integrated circuits. The process of selective epitaxial depositions of high purity single-crystal GaAs with various doping concentrations into semi-insulating GaAs substrates has been developed. These high-resistivity substrates (>10⁶ohm.cm) provide the electrical isolation between devices, eliminating the difficulties and deficiencies normally encountered in trying to obtain isolation with dielectrics, back-etching, p-n junctions, etc. This monolithic approach to integrated-circuits thus allows for improved microwave pedormance from the devices since parasitics are reduced to a minimum. Planar Gunn oscillators and Schottky barrier diodes have been fabricated for use in a completely monolithic integrated millimeter wave (94 GHz) receiving front end. The Gunn oscillators are made in a sandwich-type structure of three selective deposits whose carrier concentrations are approximately 10¹⁸-10¹⁵-10¹⁸cm^-3. The Schottky diodes consist of two deposits with concentrations of 10¹⁸and 10¹⁷cm^-3. The Schottky contact is formed by evaporating Mo-Au onto the 10¹⁷cm^-3deposits; all ohmic contacts are on the surface and are alloyed to the N⁺regions.     

Measurement techniques for monolithic microwave integrated circuits

Introduces the basic technologies that are associated with measurements of monolithic microwave integrated circuits. The use of test fixtures and wafer probe stations at ambient room temperature is reviewed and their role at thermal and cryogenic temperatures is discussed. With the increasing need for performing non-invasive measurements, advances in experimental field probing techniques are explored     

Uniplanar techniques for monolithic microwave integrated circuits

`Uniplanar' techniques have recently been introduced for the design of monolithic microwave integrated circuits (MMICs). The aim of these techniques is to achieve a higher level of integration of circuitry and to overcome the need for through-substrate via holes and the related back-face processing steps. This is achieved by using coplanar waveguide (CPW), slotline, and miniature `thin-film microstrip' transmission-line media as opposed to conventional microstrip. The design and performance of a number of uniplanar MMIC couplers, amplifiers, and other test circuits fabricated using the GEC-Marconi (Caswell) foundry are described