Two-port Measurements Research Articles

Suppression of GHz range power/ground inductive impedance and simultaneous switching noise using embedded film capacitors in multilayer packages and PCBs

We measured and demonstrated the great advantages of embedded film capacitors in reducing power/ground inductive impedance and the suppression of SSN at frequencies up to 3 GHz for high-performance multilayer packages and PCBs. Eight-layer test PCBs were fabricated, and their inductive power/ground network impedances were measured as a function of film thickness, via distribution, and combined use with discrete decoupling capacitors, using a two-port self-impedance measurement method. This successfully demonstrated that the power/ground inductive impedance was reduced from 270 pH to 106 pH simply by using an embedded film capacitor instead of 16 discrete decoupling capacitors.

Accurate determination of the complex permittivity of materials with transmission reflection measurements in partially filled rectangular waveguides

An enhanced transmission reflection technique for the precise determination of the complex permittivity of dielectric materials partially filling the cross section of a rectangular waveguide is described. Dielectric properties are determined by an iterative procedure from two-port S-parameter measurements and a numerically generated propagation constant obtained from the analysis of a partially filled waveguide. Convergence of the solution is ensured from perturbational approximations. Unlike previous approaches, an uncertainty investigation is performed, taking into account all the parameters involved in the dielectric characterization. Permittivity accuracy values are presented and, hence, an optimum measurement setup can be established. Measurements of reference materials have been carried out to validate the method.

Simple noise deembedding technique for on-wafer shield-based test fixtures

Conventional on-wafer test fixtures have a significant impact on two-port noise-parameter measurements of silicon devices at gigahertz frequencies. This leads to increased measuring inaccuracy, as well as a need for complicated and area-consuming deembedding procedures. Alternatively, shield-based test fixtures are characterized by very few series effects and, thus, support cost-efficient and simple deembedding. The applicability of a simple one-step method is illustrated with experimental data. A performance comparison is made to full-scale deembedding methods based on conventional, as well as shield-based test fixtures.

An accurate interface for capacitive sensors

A new smart interface based on a first-order charge-balanced SC-oscillator is presented for capacitive sensors, which are shunted by a parasitic conductance. In the novel interface, the effect of shunting conductance is reduced by using the charge/discharge method. The effect of the stray capacitances is eliminated by using the two-port measurement. Moreover, all multiplicative and additive errors of the interface are also eliminated by using the auto-calibration technique and the chopping technique.

Straightforward and accurate nonlinear device model parameter-estimation method based on vectorial large-signal measurements

To model nonlinear device behavior at microwave frequencies, accurate large-signal models are required. However, the standard procedure to estimate model parameters is often cumbersome, as it involves several measurement systems (DC, vector network analyzer, etc.). Therefore, we propose a new nonlinear modeling technique, which reduces the complexity of the model generation tremendously and only requires full two-port vectorial large-signal measurements. This paper reports on the results obtained with this new modeling technique applied to both empirical and artificial-neural-network device models. Experimental results are given for high electron-mobility transistors and MOSFETs. We also show that realistic signal excitations can easily be included in the optimization process.

Microwave frequency interconnection line model of a wafer level package

In this paper, we introduce the microwave transmission characteristics of interconnection lines on a wafer level package (WLP) and also propose a precise microwave-frequency model of the WLP interconnections. The slow wave factor (SWF) and attenuation constant are measured and discussed. High-frequency measurement is described, based on two-port S-parameter measurements, using an on-wafer microwave probe with a frequency range of up to 5 GHz. The extracted model is represented in the form of distributed lumped circuit model elements and can be easily merged into SPICE simulations. From the extracted model, it was found that line capacitance and inductance per unit length are 0.110 pF/mm and 0.286 nH/mm, respectively. We have successfully applied the extracted model to the design and analysis of a Rambus memory module for time domain simulation and signal integrity simulation. From the simulation, it was found that the WLP has better high-frequency performance, because of its low package inductance, compared with the /spl mu/BGA package, but longer propagation delay, because of the relatively high package capacitance.

Broadband modeling and measurement of the signal behavior in S/390 MCM packages

In this work, we investigate the electrical performance of critical signal paths in IBM's S/390 MCM packages. We present lumped RLC-models suitable for standard circuit simulators like e.g. SPICE. The models are developed from finite element simulations of typical signal path segments. By comparing S-parameters from simulations of the models to two-port network analyzer measurements we validate the models in a frequency range up to 3 GHz.

Large‐signal modelling and measuring go hand‐in‐hand: Accurate alternatives to indirect S‐parameter methods (invited paper)

Classical large-signal device models are indirectly derived from small-signal S-parameter measurements. Due to the availability of the nonlinear network measurement system (NNMS), models can be based directly upon full two-port large-signal measurements, resulting in higher model accuracy. In this article, we discuss three large-signal measurement-based modelling approaches. ©2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 6–18, 2000.

A bilateral lightwave network analyzer-architecture and calibration

The first bilateral lightwave network analyzer (BLNA) architecture that is capable of two-port S-parameter measurements is reported in this paper. A combined two-tier calibration is proposed and implemented for electrooptic and optoelectronic measurements. Calibrated measurement results showing the good performance of the BLNA for all types of lightwave components are also presented.

Large-signal modelling and measuring go hand-in-hand: Accurate alternatives to indirect S-parameter methods (invited paper)

Classical large-signal device models are indirectly derived from small-signal S-parameter measurements. Due to the availability of the nonlinear network measurement system (NNMS), models can be based directly upon full two-port large-signal measurements, resulting in higher model accuracy. In this article, we discuss three large-signal measurement-based modelling approaches. ©2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 6–18, 2000.

Active probes for network analysis within 70-230 GHz

This paper presents a vector network analyzer system for the 70-230-GHz bandwidth. The instrument employs active probes for millimeter-wave signal generation and detection, and for signal delivery to the device-under-test. Milimeter-wave signals are generated and detected within the active probes using an integrated circuit (IC) based on nonlinear transmission lines. The IC contains all elements of an S-parameter test set: a multiplier to generate the radio-frequency signal, directional couplers to separate the incident and reflected waves, and a pair of high-speed sampling circuits to convert the signals down to lower frequencies. Two-port measurements over the 70-230-GHz bandwidth are demonstrated, including those of directional couplers and millimeter-wave high electron-mobility transistors.

Dielectric plug-loaded two-port transmission line measurement technique for dielectric property characterization of granular and liquid materials

There are numerous dielectric property characterization techniques available in the microwave regime each with its own uniqueness, advantages and disadvantages. The two-port completely-filled waveguide (transmission line) technique is a robust measurement approach which is well suited for solid dielectric materials. In this case, the dielectric material can be relatively easily machined to fit inside the waveguide and the subsequent measurement of the scattering parameters of this two-port device renders the dielectric properties of the material filling the waveguide. However, this technique is not well suited for measuring the dielectric properties of granular and liquid materials. These materials are used in the production of various composites which are increasingly replacing the use of metals in many environments. If this technique is directly applied to these types of materials, several approximations either in the measurement apparatus or the formulation must be made. To overcome this problem, this paper describes a modification to this measurement technique utilizing two dielectric plugs which are used to house the granular or the liquid dielectric material. In this approach no approximation to the measurement apparatus is made while the presence of the plugs are fully accounted for in the derivations. Using this technique, the dielectric properties of cement powder, corn oil, antifreeze solution and tap water, constituting low- and high-loss dielectric materials (granular and liquid) were measured. In addition, the important issue of measurement uncertainty associated with this technique is also fully addressed. The issue of optimal choice of various measurement parameters is also discussed as it relates to the measurement uncertainty.

An innovative modelization of loss mechanism in silicon integrated inductors

In this paper, we present an improved lumped-element equivalent circuit of silicon integrated inductors, which accurately takes into account parasitic effects and separately models the effect of metal and substrate losses. We describe an efficient procedure to deduce all the elements of the equivalent circuit from wideband, two-port measurements of the S-parameters of the inductor. The separate characterization of metal and substrate losses allows us to evaluate separately their contribution to the inductor's Q-factor. We also report the results of the characterization of some CMOS and BiCMOS integrated inductors designed to be included in radio frequency integrated circuits operating at 1.8 GHz.

Flow-through coaxial sample holder design for dielectric properties measurements from 1 to 350 MHz

A system for measuring the dielectric properties of cereal grains from 1 to 350 MHz with a coaxial sample holder is presented. A signal-flow graph model was used to determine the permittivity of several polar alcohols from the full two-port S-parameter measurements. At the lowest frequencies 1-25 MHz where the phase measurements are less accurate, a lumped-parameter model was used to predict the dielectric loss factor values. The system was calibrated with measurements on air and decanol and verified with measurements on octanol, hexanol, and pentanol. The standard error for the polar alcohols used for verification was 2.3% for the dielectric constant and 7.6% for the dielectric loss factor. Although measurements were taken on static samples, the sample holder is designed to accommodate flowing grain.

Two-port noise and impedance measurements for two-terminal devices with a resonant tunneling diode example

A two-port technique is presented for determining the circuit elements and noise sources of the equivalent circuit of a two-terminal device at microwave frequencies. The two-terminal device is connected as a two-port so that intrinsic and parasitic circuit elements can be obtained from full two-port S-parameter measurements. This measurement does not require one of the two contacts to be grounded, which makes it particularly well suited for the characterization of integrated devices where parasitic elements become important and cannot be easily calculated. The noise of the device is measured by employing a noise-figure meter and the intrinsic noise is computed from the measured terminal noise. As an example, the impedance and noise elements of a resonant tunneling diode (RTD) are measured over frequency ranges of 2-8 and 2-4 GHz, respectively.

Characterization of balanced transmission line by microwave techniques

This paper presents a method of experimentally characterizing a balanced transmission line using microwave techniques. An unbalanced measurement instrument and the transmission line under test must he connected by a balun, and the effect of the balun must be removed from the measured data. Deembedding techniques are discussed briefly, and several baluns are evaluated. Two methods of performing the measurement are presented. The first uses a one-port measurement where known loads are measured from the end of various lengths of transmission line. The second uses two-port measurements with different transmission-line lengths, and is more effective for measurement of line loss. Experimental results are presented for 2 mm toughened plastic sheath (TPS) twin and earth power cable for the range of 0.3-300 MHz.

Analysis, design, and optimization of spiral inductors and transformers for Si RF ICs

Silicon integrated circuit spiral inductors and transformers are analyzed using electromagnetic analysis. With appropriate approximations, the calculations are reduced to electrostatic and magnetostatic calculations. The important effects of substrate loss are included in the analysis. Classic circuit analysis and network analysis techniques are used to derive two-port parameters from the circuits. From two-port measurements, low-order, frequency-independent lumped circuits are used to model the physical behavior over a broad-frequency range. The analysis is applied to traditional square and polygon inductors and transformer structures as well as to multilayer metal structures and coupled inductors. A custom computer-aided-design tool called ASITIC is described, which is used for the analysis, design, and optimization of these structures. Measurements taken over a frequency range from 100 MHz to 5 GHz show good agreement with theory.

MEASURING DIELECTRIC PROPERTIES OF HARD REDWINTER WHEAT FROM 1 TO 350 MHZ WITH A FLOW-THROUGH COAXIAL SAMPLE HOLDER

A system for measuring the dielectric properties of cereal grains from 1 to 350 MHz with a coaxial sample holder is presented. Several polar alcohols were used to calibrate and verify permittivity measurements obtained with a signal-flow graph model from the full two-port S-parameter measurements. At the lowest frequencies (1-25 MHz), where the phase measurements are less accurate, a lumped parameter model was used for the dielectric loss factor measurements. The system was calibrated with measurements on air and decanol and verified with measurements on octanol, hexanol, and pentanol. The standard error for the polar alcohols used for verification was 2.3% for the dielectric constant and 7.6% for the dielectric loss factor. Although measurements were taken on static samples, the sample holder is designed to accommodate flowing grain. Dielectric properties measurements at 25°C were taken on four hard red winter wheat cultivars ranging in moisture content from about 9% to 21% with bulk densities varying from 0.66 to 0.83 g/cm3. Most of the data agreed with measurements reported in the literature.

A simple error correction method for two-port transmission parameter measurement

This letter presents a simple error correction method for two-port transmission parameter measurement. The method requires measuring only two nonreflecting transmission lines instead of a complete set of calibration standards (at least three) for error correction, it does not need an explicit solution of error coefficients. These two features make it simpler than any other methods. Error-corrected measurement results of a CPW discontinuity using the new method and the TRL method are in good agreement. The new method is useful in characterizing well-matched two-port devices or those whose reflection parameters are of little interest.

S-parameter measurements yielding the characteristic matrices of multiconductor transmission lines

A frequency-domain method is presented, which yields accurate characteristic matrices of uniform multiconductor transmission lines (MTLs). It uses simple two-port network analyzer S-parameter measurements of a set of open-circuit and short-circuited MTL configurations. The method eliminates the need for voltage and current probes, which introduce errors. Transversely inhomogeneous MTLs can be accurately characterized in their quasi-TEM propagation regime. The influence of the skin effect on the inductance matrix is taken into account. The technique was used to determine the inductance and capacitance matrices of a low-loss three-conductor ribbon cable above a ground plane. Comparisons with numerically and analytically obtained data are given. Measurements are found to be repeatable for lines of length /spl Lscr/</spl lambda//4. The /spl lambda//4 requirement is not found to be a restriction in the megahertz regime and only plays a role as line-end effects become significant at gigahertz frequencies. The obtained accuracy is significantly better than previously reported results.