Simple and accurate approaches to implement the complex trans‐conductance suited for time‐domain simulators for small‐signal and large‐signal table‐based models

Abstract

SUMMARYThis paper focuses on the implementation of table-based models of high-frequency transistors for timedomain simulators at microwave and mm-wave frequencies. In this frequency range, the channel is not capable of responding to the excitation instantaneously therefore, a delay-time exists between the channel response and the channel excitation. This delay is represented by a complex trans-conductance in terms of circuit elements. The high-frequency models of transistors are required to have the implementation of complex trans-conductance, where the complex part accounts mathematically for the delay-time between the channel response and the channel excitation. This paper presents simple and accurate approaches to incorporate the complex trans-conductance in both small-signal and large-signal table-based models for time-domain simulators (MOS-AK International Meeting. Eindhoven, Netherlands, April 2008). Implementation approach for each model, small-signal and large-signal, is presented in separated sections. In the first step, the delay is realized by the introduction of an ideal transmission line between the channel excitation and the channel response. As transmission lines are not generally suitable for time-domain simulations, a lumped element equivalent network is introduced in the second step. The latter approach is fully compatible with time-domain simulators but frequency limitation, determined by the delay-time value itself, is introduced. Then the implementation of the complex trans-conductance in large-signal model is introduced. In terms of large-signal behavior, delay-time is important to achieve a non-quasi static model. Yet again there is limitation in terms of the frequency range that is determined by the delay value itself. The methodology is illustrated on the small-signal and the large-signal equivalent circuit of a Multi-Fin MOSFET transistor. Simulations are carried out by Cadence Spectre and Agilent ADS simulators, and comparisons are carried out between the simulation results and the measurements.

Microwave neural modeling for silicon FinFET varactors

“…Contrary to the physical and equivalent circuit models, the approach based on artificial neural networks (ANNs) allows obtaining an accurate representation of the device behavior without having to analyze the device structure or the physical processes in it. Among other applications in the field of microwaves [11][12][13][14][15][16], ANNs have been already successfully applied for small-signal and large-signal modeling of different types of high-frequency transistors, such as metal-semiconductor field effect transistor (MESFET), highelectron-mobility transistor (HEMT), metal-oxide-semiconductor field-effect transistor (MOSFET), and heterojunction bipolar transistor (HBT) [17][18][19][20][21][22][23][24][25][26][27][28][29][30] as well as FinFET transistor [31][32][33], which represents an innovative multiple-gate architecture for the downscaling of the complementary metal-oxidesemiconductor technology [34][35][36][37][38]. The present study is aimed at presenting the results achieved by using the ANNs for modeling the scattering (S-) parameters up to 50 GHz for a varactor realized in the advanced FinFET technology, which has already been represented with an equivalent circuit model [9].…”