Extending scattering-parameter approach to characterization of linear time-varying microwave devices

Abstract

In this paper, we apply the theory of linear time-varying differential systems of equations to defining an extension of the standard scattering parameters. This extended parameter~() is a function of both time and frequency. With this definition, we can accurately characterize rapidly timeand frequency-varying linear lumped causal microwave devices, in particular, photoconductive microwave switches. We discuss the similarities between~() and the standard-parameter approach and describe a measurement technique. We also derive some important properties of the~()-parameters and describe conditions under which microwave devices such as photoconductive switches can be analyzed by this technique. To demonstrate the usefulness of~(), we derive the complete transfer function of the time-varying lumped-element model of a photoconductive switch. We also show the limitations of conventional time-invariant assumptions (based on windowing or apodization) to accurately model linear time-varying devices.

Determining the Electrical Charging Speed Limit of ReRAM Devices

“…This is explained in detail in section III. This approach is commonly used for high frequency applications [29]- [32]. As described above the VCM stack of the devices constitutes a plate capacitor with a characteristic charging time.…”

Ultrafast charge carrier dynamics in organic (opto)electronic materials

“…The S-parameters were calculated by the electromagnetic modeling tool High Frequency Structure Simulator (HFSS) and used to describe the structural response of the switch as transimpedance function between the current generated in the unknown material and the output signal propagating along the transmission line. Previous approaches based on a description of the switch by S-parameters (Green and Sobolewski, 2000;Tripon-Canseliet et al, 2006) were fundamentally different since they aimed at computing the transfer between input and output ports rather than representing the active area by a current generator and describing the effect of the structure as a transimpedance.…”

Influence of Measured Scattering Parameters on the Convolution Simulation of Nonlinear Loaded High-Speed Microstrip Interconnects

“…In (12) and (13), V g denotes the Fourier transform of the voltage source v g (t); F −1 denotes the inverse Fourier transform and " * " stands for convolution. S 11 , S 12 , S 21 and S 22 are the S-parameters of the interconnect.…”

“…By the same time, Djordjevic et al [5,6] analyzed time-domain responses of multiconductor transmission lines by means also of convolution. Afterward, a plethora of researchers [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] presented different applications of the convolution concept to simulate linearly and nonlinearly terminated transmission lines and high-speed microstrip interconnects. A more complete representation for the microstrip interconnects, based on a time-domain RLCG-model instead of the classic frequency-domain S-parameter-model was introduced in [23].…”