SPICE-Compatible Equivalent Circuit Models for Accurate Time-Domain Simulations of Passive Photonic Integrated Circuits

Abstract

Passive photonic integrated circuits (PICs) can be easily characterized in the frequency-domain, but their accurate time-domain performance evaluation is a hurdle for systemlevel designers, especially when dealing with resonant circuits having highly dispersive behavior, such as ring resonators. In this paper, a new equivalent circuit modeling and simulation approach is proposed, based on the Complex Vector Fitting algorithm, able to perform accurate and robust time-domain simulations of passive PICs directly in standard SPICE simulators. The proposed modeling technique starts from scattering parameters of passive PICs, and is able to capture linear and high order dispersion, backscattering, and wavelength dependent effects. Considering the different nature of optical and electronic signals, a novel concept of equivalent voltage and current for optical waveguides is proposed to simplify the optical to electronic ports conversion and to make it possible to connect and terminate the equivalent circuit models as needed in SPICE simulators, natively supporting bidirectional signal propagation in a waveguide. This work provides a precise and reliable solution to evaluate timedomain characteristics of passive PICs and to access any internal nodes within a circuit, such as the signals inside a ring resonator. Three examples of time-domain simulations of passive PICs in commercial SPICE simulators are presented to demonstrate the flexibility and advantages of the proposed technique.

Wideband parametric baseband macromodeling of linear and passive photonic circuits via complex vector fitting

“…To demonstrate the compatibility of the proposed modeling framework with various circuit simulators, the optimized macromodel is also simulated in Caphe and SPICE. For conversion of the CVF model to a SPICE-compatible netlist, we refer the reader to our previous work 41 . Note that the poles of the state-space model must be shifted before building the equivalent electrical netlist.…”

“…The computational time required to simulate the model ( 22 ) in Caphe and SPICE is 2.41 s and 4.85 s respectively. The simulation in SPICE is less efficient, as it is a modified nodal solver and falls into the category of regular ODE solvers 41 . As already highlighted in the previous example, the same can be said about Caphe’s ODE solver.…”

“…Moreover, it’s important to note that SPICE-based solvers do not directly accept differential equations as input. For a detailed discussion on how to convert a CVF macromodel into an equivalent electrical network and how to simulate this equivalent circuit within a SPICE environment, the reader is referred to the author’s previous work 41 . Note that we refer to macromodels that combine the wideband macromodeling approach with the parametric macromodeling technique as wideband parametric baseband macromodels .…”

Introducing SPECS: scalable photonic event-driven circuit simulator

“…Photonic simulations rely on a multi-level abstraction methodology similar to the one prevalent in electronics [4] , and in fact re-purposes many tools from the electronic design automation (EDA) portfolio [5]- [7] . At the device level, 2D/3D electromagnetic simulations provide detailed information about the behavior of individual components.…”

Compact photonic model based on coupled-mode theory for nonlinear interactions in electronic-photonic co-simulation

“…Many behavioral macro models for photonic devices based on Verilog-A [14,15,[18][19][20][21][22] or SPICE [23][24][25] are also proposed to perform the pre-silicon validation of photonic components along with electronic circuits entirely within the EDA environment. They have been proven effective and efficient and can be used by IC designers to design EPHICs on mature EDA platforms such as Cadence Virtuoso [14,18,21,[25][26][27].…”