Reydezel Torres-Torres

Impedance Matching of Traces and Multilayer via Transitions for On-Package Links

A method for achieving impedance matching between traces and multilayer via transitions in on-package chip-to-chip links is presented. The method allows determining of the geometry for minimizing the return loss when a signal propagates through the link. For this purpose, analytical equations are derived using a physically-based equivalent circuit to represent the input impedance of multilayer via transitions. S -parameter measurements performed to optimized links using the method demonstrate the usefulness of the proposal.

Characterization of Electrical Transitions Using Transmission Line Measurements

An analytical methodology for characterizing electrical transitions associated with transmission line-based microwave channels is presented in this paper. The methodology is formulated using ABCD matrixes obtained from S-parameters measured to two lines with different length and terminated with the transition under investigation. This allows to determine the two-port network parameters of the transition in a simple and direct way. Excellent results are obtained when characterizing coplanar waveguide-to-microstrip and coaxial-to-microstrip transitions. Moreover, the methodology was also successfully applied to obtain the network parameters of packages fabricated on printed circuit board technology.

Modeling Resonances in Transmission Lines Fabricated Over Woven Fiber Substrates

This paper models transmission lines (TLs) fabricated over a printed circuit board substrate made of woven fiber fabric that causes resonances in the insertion and return loss. The modeling relies on the fact that these lines can be analyzed as periodically loaded TLs. Here, a method to determine the associated equivalent propagation constant and characteristic impedance is proposed. This allows to accurately reproduce the S-parameters for a TL of arbitrary length and for any periodicity of the fiber weave pattern along the line requiring neither multi-staged equivalent circuits, nor full-wave simulations.

Characterization of RF-MOSFETs in Common-Source Configuration at Different Source-to-Bulk Voltages From S-Parameters

Using a new test fixture that allows us to bias the bulk terminal through an additional compensated DC probe, a two-port S-measurement-based methodology to characterize RF-MOSFETs in common-source configuration is herein presented. In addition to obtaining S-parameters at different bulk-to-source voltages using a single two-port configured test-fixture, the proposal allows the analysis of the electrical parameters of a MOSFET that are influenced by the substrate effect when the frequency rises. Physically expected results are obtained for devices model parameters, allowing to accurately reproduce S-parameters up to 20 GHz. Furthermore, extracted parameters, such as threshold voltage, are in agreement with those obtained using well-established DC methods. This method allows one to characterize a four-terminal MOSFET from two-port small-signal measurements.

An approach for quantifying the conductor and dielectric losses in PCB transmission lines

An experimental method for separately determining the contribution of the conductor and dielectric losses to the signal attenuation occurring in PCB transmission lines is presented in this paper. This method is based on an analytical extraction of the model parameters for the propagation constant and takes into consideration the dominant effects influencing the signal attenuation. It is demonstrated through a careful model-experiment correlation that the application of this method allows the accurate representation of the loss mechanisms in PCB technology. Furthermore, the frequency beyond which the dielectric losses surpass the skin effect losses is also easily determined in a simple and direct way using the proposed method.

Impact of multi-finger geometry on the extrinsic parasitic resistances of microwave MOSFETs

Multi-Finger MOSFETs are used to decrease the gate resistance in order to improve microwave-operation figures-of-merit such as the maximum frequency of oscillation. Even though the effect of splitting the gate electrode on the associated resistance has been extensively analyzed, the corresponding influence on the source-drain resistances has not been the subject of much research. We herein present an analysis of the series parasitic resistances of MOSFETs with different number of fingers.

Impact of the Configuration of Ground Vias on the Performance of Vertical Transitions Used in Electronic Packages

The ground vias are used to interconnect the different ground planes existing in a package structure, but also to prevent the propagation of parasitic modes like the parallel-plate mode inside the structure. From a signal integrity perspective, these parasitic modes degrade and limit the performance of a package since they introduce undesired resonances in the electrical response of the structure. Thus, the distribution of the ground vias is of great importance in the design of advanced packages. Using full-wave simulators, we have observed the distribution of the electric and magnetic fields as a high-frequency signal propagates through vertical transitions surrounded by ground vias. The information from the distribution of fields and the corresponding S-parameters were obtained from simulations for different configurations of ground vias in a vertical transition; these are the bases of the paper. The purpose of the presented analysis is to understand the relationship between the frequency at which the resonances associated with the propagation of parasitic modes occur and the configuration of the ground vias.

Characterization and modeling of electronic packages using S-parameters

In this paper, we demonstrate the feasibility to characterize and model singled-ended electronic packages using experimental S-parameters up to 30 GHz. TRL calibration and transmission line theory techniques were applied to obtain the two-port network parameters of the packages from measurements performed to package-to-transmission line test structures. With this information, an assessment of the performance of the package was carried out, as well as the development of equivalent circuit models to represent this structure up to 30 GHz. The methodology is explained step-by-step including the description of the required prototypes. Excellent agreement of the resulting models with experimental data validates the proposed methodology.

Consistent DC and RF MOSFET Modeling Using an

This paper demonstrates the feasibility of using data extracted from experimental S-parameters to implement models to accurately represent MOSFET behavior under DC and RF regimes with consistency. For this purpose, a method to extract the MOSFETs drain-to-source conductance, the subthreshold swing, the source/drain resistance, the effective gate length, and the threshold voltage is proposed. The method is based on the determination of the inverse of the channel resistance that is directly related to the previously mentioned parameters. Hence, two-port S-parameter measurements of common-source configured RF-MOSFETs with different gate lengths are performed, varying the gate-to-source voltage from the subthreshold region to strong inversion. In order to verify the validity and consistency of the method, excellent correlation of DC and RF models with experimental data is achieved.

S

A complete methodology to characterize substrate integrated waveguide (SIW) structures from S-parameter measurements is presented. We determined the complex propagation constant, the characteristic impedance of a homogeneous section of waveguide, and the efficiency of different adapters used to launch the signals into the waveguide. After a detailed analysis, it is observed that the most significant losses in an SIW are associated with the adapters since a low insertion loss is presented in a homogeneous section of waveguide