A design-oriented methodology for accurate modeling of on-chip interconnects

An accurate modeling methodology for typical on-chip interconnects used in the design of high frequency digital, analog, and mixed signal systems is presented. The methodology includes the parameter extraction procedure, the equivalent circuit model selection, and mainly the determination of the minimum number of sections required in the equivalent circuit for accurate representing interconnects of certain lengths within specific frequency ranges while considering the frequency-dependent nature of the associated parameters. The modeling procedure is applied to interconnection lines up to 35 GHz obtaining good simulation-experiment correlations. In order to verify the accuracy of the obtained models in the design of integrated circuits (IC), several ring oscillators using interconnection lines with different lengths are designed and fabricated in Austriamicrosystems 0.35 μm CMOS process. The average error between the experimental and simulated operating frequency of the ring oscillators is reduced up to 2% when the interconnections are represented by the equivalent circuit model obtained by applying the proposed methodology.     

直接注入模式可见光和红外传感器的注入效率

固体成像传感器包括可见光CCD,IRCCD,CMOS和红外焦平面阵列,其信号由光电二极管经注入栅沟道直接输入到转移级是基本的注入模式.本文总结了近30年来的发展成果,阐述了直接注入效率的理论和基本公式,得出在取样频率低的情况下,增大注入栅的跨导和光电二极管的阻抗是提高注入效率的最有效方法;在光电二极管低阻抗的情况下,采用电流镜像直接注入新设计,其注入栅的跨导可趋于无限大,因而可使注入效率接近100%.分析了电路的新设计方法,研制了64元线列InSb电流镜像直接注入电路.初步测试表明,注入效率与理论分析接近.     

A comprehensive 2-D inductance modeling approach for VLSI interconnects: frequency-dependent extraction and compact circuit model synthesis

Although three-dimensional (3-D) partial inductance modeling costs have decreased with stable, sparse approximations of the inductance matrix and its inverse, 3-D models are still intractable when applied to full chip timing or crosstalk analysis. The 3-D partial inductance matrix (or its inverse) is too large to be extracted or simulated when power-grid cross-sections are made wide to capture proximity effect and wires are discretized finely to capture skin effect. Fortunately, 3-D inductance models are unnecessary in VLSI interconnect analysis. Because return currents follow interconnect wires, long interconnect wires can be accurately modeled as two-dimensional (2-D) transmission lines and frequency-dependent loop impedances extracted using 2-D methods . Furthermore, this frequency dependence can be approximated with compact circuit models for both uncoupled and coupled lines. Three-dimensional inductance models are only necessary to handle worst case effects such as simultaneous switching in the end regions. This paper begins by explaining and defending the 2-D modeling approach. It then extends the extraction algorithm to efficiently include distant return paths. Finally, a novel synthesis technique is described that approximates the frequency-dependent series impedance of VLSI interconnects with compact circuit models suitable for timing and noise analysis.     

Conducted electromagnetic emissions in induction motor drivesystems. II. Frequency domain models

For pt.I see ibid., vol.13, no.4, p.757-67 (1998). Predicting conducted emissions in pulsewidth modulation (PWM) inverter induction motor drive systems requires various frequency-dependent effects to be considered. A frequency domain method has advantages in such cases compared to a time domain approach. Based on the modal analysis presented in Part I, this paper develops frequency domain models to evaluate the spectra of the conducted emissions directly. The common and differential mode excitation sources are modeled in the frequency domain and related to the switching functions of the PWM inverter. Network models are established where the induction motor is represented using its frequency-dependent impedance characteristics, which can be obtained from measurements. The influences of system unbalances and of transmission-line effects due to long cables are investigated. Predicted emission spectra are compared with laboratory measurements and those derived from the time domain simulation. It is found that the agreement is good. The proposed method allows emission spectra to be predicted without recourse to specialist circuit simulators     

Resonance characteristics of a cavity-operated electrodelesshigh-pressure microwave discharge system

To characterize the resonance behavior of cavity-operated electrodeless high-pressure microwave discharge systems, a microwave circuit is developed that allows high-power network analysis during the operation of the discharge. The frequency-dependent complex impedance of the cavity including the plasma is obtained from a reflection measurement in the range 1.5 GHz-4.5 GHz. This method allows an observation of the actual resonance frequency and the actual vectorial mismatch so that a coupling efficiency >99% can always be achieved with proper adjustment of the operation frequency and coupling probe. Experimental results with a cylindrical TM₀₁₀ cavity and a coaxially situated discharge show a decrease of the resonance frequency with increasing power (increasing plasma temperature, electron density, and electrical conductivity) depending on the discharge geometry and the plasma composition. In accordance with a simple one-dimensional model, the Q factor passes through a minimum at medium power levels, where the cavity discharge system absorbs the microwave energy most effectively     

Frequency-dependent mutual resistance and inductance formulas for coupled IC interconnects on an Si-SiO2 substrate

A highly accurate closed-form approximation of frequency-dependent mutual impedance per unit length of a lossy silicon substrate coplanar-strip IC interconnects is developed. The derivation is based on a quasi-stationary full-wave analysis and Fourier integral transformation. The derivation shows the mathematical approximations which are needed in obtaining the desired expressions. As a result, for the first time, we present a new simple, yet surprisingly accurate closed-form expression which yield accurate estimates of frequency-dependent mutual resistance and inductance per unit length of coupled interconnects for a wide range of geometrical and technological parameters. The developed formulas describe the mutual line impedance behaviour over the whole frequency range ( i.e. also in the transition region between the skin effect, slow wave, and dielectric quasi-TEM modes). The results have been compared with the reported data obtained by the modified quasi-static spectral domain approach and new CAD-oriented equivalent-circuit model procedure.     

Chip Impedance Evaluation Method for UHF RFID Transponder ICs over Absorbed Input Power

Based on a de‐embedding technique, a new method is proposed which is capable of evaluating chip impedance behavior over absorbed power in flip‐chip bonded UHF radio frequency identification transponder ICs. For the de‐embedding, four compact co‐planar test fixtures, an equivalent circuit for the fixtures, and a parameter extraction procedure for the circuit are developed. The fixtures are designed such that the chip can absorb as much power as possible from a power source without radiating appreciable power. Experimental results show that the proposed modeling method is accurate and produces reliable chip impedance values related with absorbed power.     

Analytical wide-band modeling of high frequency resistance in integrated spiral inductors

For integrated spiral inductor synthesis, designers and design automation tools require efficient modeling techniques during the initial design space exploration process. In this paper, we introduce an analytical frequency-dependent resistance model for integrated spiral inductors. Based on our resistance formulation, we have developed a systematic technique for creating wide-band circuit models for accurate time domain simulation. The analytical resistance model provides a fast alternative to field solver-based approaches with typical errors of less than 2.6 percent while surpassing the accuracy of several other analytical modeling techniques by an order of magnitude. Furthermore, the wide-band circuit generation technique captures the frequency-dependent resistance of the inductor with typical errors of less than 3.2 percent.     

Modal technique for the time domain analysis of crosstalk betweencoaxial cables

A study of current dominant coupling in a system comprising a large number of mutually coupled braided coaxial transmission lines is presented. An efficient model for the crosstalk is developed in the frequency domain using distributed circuit parameters and the concept of transfer impedance. The lines are assumed to be lossy and to have frequency-dependent per-unit-length parameters, and further losses due to the braided nature of the outer conductors are account for in the analysis. The validity of the coupling model is tested against measurements in the frequency domain before using fast Fourier transforms to evaluate the time domain responses     

Accurate parametric modeling of folded waveguide circuits for millimeter-wave traveling wave tubes

In this paper, results of different models are compared for calculating effective, cold-circuit (beam-free) phase velocities and interaction impedances of folded waveguide (FW) slow wave circuits for use in millimeter-wave traveling wave tubes (TWT). These parameters are needed for one-dimensional (1-D) parametric model simulations of FW traveling wave tubes (FWTWTs). The models investigated include approximate analytic expressions, equivalent circuit, three-dimensional (3-D) finite difference, and 3-D finite element. The phase velocity predictions are compared with experimental measurements of a representative FW circuit. The various model results are incorporated into the CHRISTINE1D code to obtain predictions of small signal gain in a 40-55 GHz FWTWT. Comparing simulated and measured frequency-dependent gain provides a sensitive, confirming assessment of the accuracy of the simulation tools. It is determined that the use of parametric 1-D TWT models for accurate, full band predictions of small signal gain in FWTWTs requires knowledge of phase velocity and impedance functions that are accurate to <0.5% and <10%, respectively. Saturated gain predictions, being approximately half as sensitive to these parameters, appear to require correct specification of phase velocity and interaction impedance to within /spl sim/1% and 20%, respectively. Although all models generate sufficiently accurate predictions of the interaction impedance, not all generate sufficiently accurate predictions of the effective axial phase velocity.     

Equivalent Circuit Model of a Bundle of Cables for Bulk Current Injection (BCI) Test

A "simulation program with integrated circuit emphasis" (SPICE) model for the evaluation, in frequency and time domain, of the coupling of a bundle of shielded coaxial cables with an external electromagnetic source such as a bulk current injection clamp, is developed. The proposed equivalent circuit takes into account the presence of the transfer impedance and the presence of the transfer admittance, and it does not need the subdivision in elementary cells. Intermediate results are validated by comparing the exact numerical solutions with the output of the SPICE circuit, and the final results are validated by means of comparison with measurements carried out on an experimental setup. The feature selective validation (FSV) technique is used as a measure of the comparisons     

Generating compact, guaranteed passive reduced-order models of 3-D RLC interconnects

As very large scale integration (VLSI) circuit speeds and density continue to increase, the need to accurately model the effects of three-dimensional (3-D) interconnects has become essential for reliable chip and system design and verification. Since such models are commonly used inside standard circuit simulators for time or frequency domain computations, it is imperative that they be kept compact without compromising accuracy, and also retain relevant physical properties of the original system, such as passivity. In this paper, we describe an approach to generate accurate, compact, and guaranteed passive models of RLC interconnects and packaging structures. The procedure is based on a partial element equivalent circuit (PEEC)-like approach to modeling the impedance of interconnect structures accounting for both the charge accumulation on the surface of conductors and the current traveling in their interior. The resulting formulation, based on nodal or mixed nodal and mesh analysis, enables the application of existing model order reduction techniques. Compactness and passivity of the model are then ensured with a two-step reduction procedure where Krylov-subspace moment-matching methods are followed by a recently proposed, nearly optimal, passive truncated balanced realization-like algorithm. The proposed approach was used for extracting passive models for several industrial examples, whose accuracy was validated both in the frequency domain as well as against measured time-domain data.     

A comprehensive compact-modeling methodology for spiral inductors in silicon-based RFICs

A new comprehensive wide-band compact-modeling methodology for on-chip spiral inductors is presented. The new modeling methodology creates an equivalent-circuit model consisting of frequency-independent circuit elements. A fast automated extraction procedure is developed for determining the circuit element values from two-port S-parameter measurement data. The methodology is extremely flexible in allowing for accurate modeling of general classes of spiral inductors on high- or low-resistivity substrate and for large spirals exhibiting distributed trends. The new modeling methodology is applied to general classes of spirals with various sizes and substrate parameters. The extracted models show excellent agreement with the measured data sets over the frequency range of 0.1-10 GHz.     

Averaged modeling of PWM converters operating in discontinuousconduction mode

Various aspects of averaged modeling of hard-switching pulse-width modulated (PWM) converters operating in the discontinuous conduction mode (DCM) are studied. A more streamlined modeling procedure is proposed which serves as a general framework for comparing different models. A duty ratio constraint that defines the diode conduction interval is identified to be the key to accurate prediction of high-frequency behavior. A new duty-ratio constraint is proposed that leads to full-order averaged models of DCM converters. Numerical analyses and experimental measurements confirm that the new models correctly predict the small-signal responses up to one third of the switching frequency and are more accurate than all previous models. Moreover, new analytical results are included to show the origin of the high-frequency pole in DCM operation and to explain why the full-order model is capable of accurately predicting it. Averaged circuit counterparts of the new models are developed in the form of averaged switch models to facilitate circuit simulation     

Modeling of a quasi-optical Josephson oscillator

The authors have developed a computer model of a Josephson tunnel junction embedded in a general circuit with frequency-dependent impedance using the harmonic balance method. This model has been applied to the analysis of a two-dimensional Josephson junction array with integrated coupling structures, called a quasi-optical Josephson oscillator. Simulations are done for a junction with dipole, slotline, and bow-tie antennas. The results show that the junction with a bow-tie antenna gives the best performance, and the output power from an array of 4000 junctions can reach 25.7 μW at a frequency as high as 1091 GHz for niobium junctions deposited on a 0.207-mm-thick quartz substrate     

Full-wave simulation of electromagnetic coupling effects in RF and mixed-signal ICs using a time-domain finite-element method

This paper describes the computer simulation and modeling of distributed electromagnetic coupling effects in analog and mixed-signal integrated circuits. Distributed electromagnetic coupling effects include magnetic coupling of adjacent interconnects and/or planar spiral inductors, substrate coupling due to stray electric currents in a conductive substrate, and full-wave electromagnetic radiation. These coupling mechanisms are inclusively simulated by solving the full-wave Maxwell's equations using a three-dimensional (3-D) time-domain finite-element method. This simulation approach is quite general and can be used for circuit layouts that include isolation wells, guard rings, and 3-D metallic structures. A state-variable behavioral modeling procedure is used to construct simple linear models that mimic the distributed electromagnetic effects. These state-variable models can easily be incorporated into a VHDL-AMS simulation providing a means to include distributed electromagnetic effects into a circuit simulation.     

Noise Source Lumped Circuit Modeling and Identification for Power Converters

In this paper, a general lumped circuit modeling method is proposed to describe the conducted electromagnetic interference (EMI) coupling mechanism for the switching power converters. The EMI characteristics of the converters can be analytically deduced from a circuit theoretical viewpoint. The shunt and series impedance insertion method is introduced to identify the differential-mode (DM) and common-mode (CM) noise impedances and voltage sources. The procedure of parameters estimation for the noise models comprises several simple measurements and is convenient to be implemented. Experimental illustrations are also included to verify the validity of the proposed method. Comparison between the measured and predicted results shows that the EMI modeling method can provide adequate prediction of the EMI feature for power-switching converters     

A Current Injection Built-In Test Technique for RF Low-Noise Amplifiers

In this paper, a practical current injection based built-in test (BIT) technique for impedance-matched RF low-noise amplifiers (LNAs) is proposed. A current generation circuit injects the RF test current at the gate of the LNA; this approach has the advantage that the matching network is not affected by the test circuitry. The technique can be used without design changes to measure the voltage gain during on-wafer test and to measure ${rm S} _{21}$ during final test in the presence of gate inductance and package parasitics. Furthermore, the current injection testing technique enables accurate gain measurements in order to detect faulty impedance matching networks. The proposed current-based BIT requires an on-chip voltage source, two on-chip power detectors (PDs), and an accurate external resistor. On-chip or external equipment resources are only required to measure the dc output of the PDs. As a proof of concept, a 2.1-GHz inductor-degenerated common-source LNA with a gain of 23.9 dB was designed in 0.13-$mu{hbox {m}}$ CMOS technology together with the BIT circuitry (14% area overhead). The gain predicted by the current injection RF BIT agrees with the simulated gain using corner models within 0.8-dB error.