3,230 research outputs found

    Computation of Conductance and Capacitance for IC Interconnects on a General Lossy Multilayer Substrate

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    In this paper a simple method for analysis and modelling of transmission interconnect lines on general lossy multilayer substrates at high bit rates is presented. The analysis is based on semi-analytical Green's function approach and recurrence relation between the coefficients of potential in n and n + 1 layers, respectively. The electromagnetic concept of free charge density is applied. It allows us to obtain integral equations between electric scalar potential and charge density distributions. These equations are solved by the Galerkin procedure of the Method of Moments. New approach is especially adequate to model 2-D layered structures with planar boundaries for frequencies up to 20GHz (quasistationary field approach). The transmission line parameters (capacitance and conductance per unit length) for the given interconnect multilayer geometry are computed. A discussion of the calculated line admittance in terms of technological and geometrical parameters of the structure is given. A comparison of the numerical results from the new procedure with the techniques presented in the previous publications are provided, too

    An equivalent circuit model of the traveling wave electrode for carrier-depletion-based silicon optical modulators

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    We propose an equivalent circuit model for the coplanar waveguide (CPW) which serves as the traveling wave electrode to drive carrier-depletion-based silicon modulators. Conformal mapping and partial capacitance techniques are employed to calculate each element of the circuit. The validity of the model is confirmed by the comparison with both finite-element simulation and experimental result. With the model, we calculate the modulation bandwidth for different CPW dimensions and termination impedances. A 3 dB modulation bandwidth of 15 GHz is demonstrated with a traveling wave electrode of 3 mm. The calculation indicates that, by utilizing a traveling wave electrode of 2 mm, we can obtain a 3 dB modulation bandwidth of 28 GHz

    Extraction of transmission line parameters and effect of conductive substrates on their characteristics

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    Abstract: The paper presents the effect of conductive or lossy silicon (Si) substrates on the frequency-dependent distributed series impedance transmission line (TL) parameters, R(ω) and L(ω). The frequency variations of these parameters of the microstrip line for four different conductivities of Si substrate are observed and compared. Keysight Technologies (formerly Agilent’s Electronic Measurement Group) Advanced Design System is used for the electromagnetic simulations of the microstrip line structures. Scattering parameters (S-parameters) based equations are used to plot the variations of series impedance parameters as a function of frequency. Furthermore, this paper explains a complete method to extract various parameters related to a TL. The work extracts the parameters of a microstrip TL model provided with the GlobalFoundries 0.13 μm SiGe BiCMOS8HP process design kit up to 100 GHz

    Distributed Modeling Approach for Electrical and Thermal Analysis of High-Frequency Transistors

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    The research conducted in this dissertation is focused on developing modeling approaches for analyzing high-frequency transistors and present solutions for optimizing the device output power and gain. First, a literature review of different transistor types utilized in high-frequency regions is conducted and gallium nitride high electron mobility transistor is identified as the promising device for these bands. Different structural configurations and operating modes of these transistors are explained, and their applications are discussed. Equivalent circuit models and physics-based models are also introduced and their limitations for analyzing the small-signal and large-signal behavior of these devices are explained. Next, a model is developed to investigate the thermal properties of different semiconductor substrates. Heat dissipation issues associated with some substrate materials, such as sapphire, silicon, and silicon carbide are identified, and thinning the substrates is proposed as a preliminary solution for addressing them. This leads to a comprehensive and universal approach to increase the heat dissipation capabilities of any substrate material and 2X-3X improvement is achieved according to this novel technique. Moreover, for analyzing the electrical behavior of these devices, a small-signal model is developed to examine the operation of transistors in the linear regions. This model is obtained based on an equivalent circuit which includes the distributed effects of the device at higher frequency bands. In other words, the wave propagation effects and phase velocity mismatches are considered when developing the model. The obtained results from the developed simulation tool are then compared with the measurements and excellent agreement is achieved between the two cases, which serves as the proof for validation. Additionally, this model is extended to predict and analyze the nonlinear behavior of these transistors and the developed tool is validated according to the obtained large-signal analysis results from measurement. Based on the developed modeling approach, a novel fabrication technique is also proposed which ensures the high-frequency operability of current devices with the available fabrication technologies, without forfeiting the gain and output power. The technical details regarding this approach and a sample configuration of the electrode model for the transistor based on the proposed design are also provided
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