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     

Geometric modeling of nonlinear RLC circuits

In this paper, the dynamics of nonlinear RLC circuits including independent and controlled voltage or current sources is described using the Brayton-Moser equations. The underlying geometric structure is highlighted and it is shown that the Brayton-Moser equations can be written as a dynamical system with respect to a noncanonical Dirac structure. The state variables are inductor currents and capacitor voltages. The formalism can be extended to include circuits with elements in excess, as well as general noncomplete circuits. Relations with the Hamiltonian formulation of nonlinear electrical circuits are clearly pointed out.     

Well-posed nonlinear problems in integrated circuits modeling

In this paper we study the problem (E) + (BC) + (IC) (see below) which represents a model for integrated circuits. We assume that the distributed parametersr(x) andc(x) are nonconstant, dielectric leakages depend on thex-coordinate as well as the voltage level, while the interconnecting multiport is nonlinear and possibly multivalued.     

Calculating nonlinear microwave circuits with undersampled time signals

An algorithm to reduce the computation time and storage space required during the analysis of microwave circuits with two or more nonharmonically related input frequencies is presented. It is very simple to implement in harmonic balance programs.<>     

Stability analysis of nonlinear microwave circuits in time domain

Frequency-domain based methods are not valid to analyze a nonlinear microwave circuit with general, arbitrary nonlinearities. Therefore, analysis of nonlinear microwave circuits in time-domain is presented. Subharmonics and instabilities can be predicted. As examples, Josephson junction and the Schottkybarrier mixer diode are discussed.     

On the modeling of highly nonlinear circuits usingtotal-variation-decreasing finite-difference schemes

This paper presents the modeling of highly nonlinear circuits using a total-variation-decreasing (TVD) difference scheme developed for the simulation of problems involving shock phenomena. In contrast to the commonly used leapfrog scheme, a second-order accurate TVD method based on the Lax-Wendroff scheme is applied to one-dimensional nonlinear transient electromagnetic-wave problems. Furthermore, for the analysis of transmission-line-based networks, an adapted inclusion of nonlinear lumped elements in such a TVD scheme is proposed. As an example, both the scattered signals of a linear transmission line loaded with a nonlinear lumped element is investigated and the formation of a shock-wave of a low-loss nonlinear transmission line with distributed diodes is studied. In the simulation results, the modeling of rapidly rising edges occurring in the time signal are demonstrated     

General noise analysis of nonlinear microwave circuits by thepiecewise harmonic-balance technique

This paper presents a self-consistent set of algorithms for the numerical computation of noise effects in forced and autonomous nonlinear microwave circuits. The analysis relies upon the piecewise harmonic-balance method, and thus retains all the peculiar advantages of this technique, including general-purposeness in the widest sense. The noise simulation capabilities include any kind of forced or autonomous nonlinear circuit operated in a time-periodic large-signal steady state, as well as microwave mixers of arbitrary topology. The limitations of the traditional frequency-conversion approach to noise analysis are overcome. The analysis takes into account the thermal noise generated in the passive subnetwork, the noise contributions of linear and nonlinear active devices, and the noise injected by sinusoidal driving sources of known statistical properties. The nonlinear noise models of two representative families of microwave devices (FET's/HEMT's and Schottky-barrier diodes) are discussed in detail, and several applications are illustrated     

Accurate Fourier transform method for almost-periodic response simulation of microwave nonlinear circuits

A generalised Fourier transform, in which an orthogonal sample selection algorithm is used, is presented for accurate simulation of the almost-periodic responses of microwave nonlinear circuits. The measured and simulated results of a MESFET amplifier show the significant improvement in accuracy.<>     

Volterra-mapping-based behavioral modeling of nonlinear circuits and systems for high frequencies

Presents and validates a discrete-time/frequency-domain approach to the problem of Volterra-series-based behavioral modeling for high-frequency systems. The proposed technique is based on the acquisition of samples of the input/output data, both of which are sampled at the Nyquist rate corresponding to the input signal. The method is capable of identifying the time-/frequency-domain Volterra kernels/transfer functions of arbitrary causal time-invariant weakly nonlinear circuits and systems operating at high frequencies subject to essentially a general random or multitone excitation. The validity and efficiency of the proposed modeling approach has been demonstrated by several examples in high-frequency applications and good agreement has been obtained between results calculated using the proposed model and results measured or simulated with commercial simulation tools.     

A new macromodeling approach for nonlinear microwave circuits basedon recurrent neural networks

A new macromodeling approach is developed in which a recurrent neural network (RNN) is trained to learn the dynamic responses of nonlinear microwave circuits. Input and output waveforms of the original circuit are used as training data. A training algorithm based on backpropagation through time is developed. Once trained, the RNN macromodel provides fast prediction of the full analog behavior of the original circuit, which can be useful for high-level simulation and optimization. Three practical examples of macromodeling a power amplifier, mixer, and MOSFET are used to demonstrate the validity of the proposed macromodeling approach     

Accurate silicon dummy structure model for nonlinear microwave FinFET modeling

The dummy test structures based de-embedding techniques allow one to quickly subtract out part of the parasitic contributions from the microwave transistor measurements without the need of explicit determination of the associated circuit model. But this means that the problem of determining the complex network representing the dummy structures is only by-passed rather than solved. Consequently, this paper is aimed at extracting accurate lumped element models for silicon “open” and “short” structures in order to extend the nonlinear microwave modeling of on-wafer FinFETs at the calibration plane corresponding to the probe tips without need of any shift of the reference plane.     

Numerical through-resistor (TR) calibration technique for modeling of microwave integrated circuits

A through-resistor (TR) calibration procedure is proposed for parameter extraction and accurate modeling of planar discontinuities and circuits by using a full-wave technique such as method of moments (MoM). This new scheme allows the effective use of a commercial electromagnetic field simulator in removing inherent numerical noises or errors in simulation, and making the parameter extraction for circuit models. A microstrip open-end and a microstrip gap are studied and effectiveness of this new scheme is verified.     

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.     

Design of broadband microwave circuits

The relation between the scattering-matrix eigenvalue phase/frequency responses and the energy stored in a general microwave junction filled with an anisotropic material can be used to facilitate the design of broadband microwave circuits. The technique of this approach is illustrated for a waveguide Y-junction circulator.     

Multivalued dynamic circuits

A new family of multivalued logic circuits is presented. These circuits exhibit some appealing features: they are the first MV dynamic operators reported in the literature, they implement the Vranesic-Smith-Lee algebra (which is specially suited for arithmetic operations), and their performance has been found to be similar to binary counterparts by simulation.     

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     

Inclusion of dispersive effects of microstrip lines in formulation using state-space approach of nonlinear microwave circuits

A method is presented to include the dispersive effects of transmission lines in microwave circuits in a formulation using a state space approach. The starting point are the IIR digital filter which approximate the forward impulse response and characteristic impedance.<>     

Statistical computer-aided design for microwave circuits

A useful methodology for microwave circuit design is presented. A statistical technique known as Design of Experiments is used in conjunction with computer-aided design (CAD) tools to obtain simple mathematical expressions for circuit responses. The response models can then be used to quantify response trade-offs, optimize designs, and minimize circuit variations. The use of this methodology puts the designer's intelligence back into design optimization while making “designing for circuit manufacturability” a more systematic and straightforward process. The method improves the design process, circuit performance, and manufacturability. Two design examples are presented in context to the new design methodology