IVCAD’s Key Features

  • Turnkey solution for un-matched RF transistors’ characterization & modeling
  • Pulsed IV and Pulsed S Parameter measurements for quasi-isothermal measurements for different bias conditions
  • Complete Load Pull characterization for model validation and Power Amplifier Design using MXE and MXP Load impedances
  • Transistor’s Compact modeling solution to ensure reliable simulation in linear and nonlinear conditions, for different temperatures
  • Simple and Rigorous patented Stability analysis tool for monolithic microwave amplifier design with enhanced performances

IVCAD 3.10 Modules

IVCAD Benefits

Developed by RF engineers for RF engineers, IVCAD is an intuitive and easy-to-operate device characterization software. It was developed to simplify the already complicated task of test engineers.

IVCAD was designed to protect the DUT and the instruments through multiple stop conditions and setup verifications. It would never start a measurement that your instruments cannot handle, avoiding test engineers wasting time in debugging.

The measurement speed is also optimized through highly optimized instrument drivers programing. Test engineers will increase their device characterization throughput without sacrificing the system's accuracy or reliability. Multiple setups can be combined in one measurement automation sequence.

A proven calibration process in vector and scalar mode embed validation and verification procedures to increase accuracy and confidence in measurements.

Multiple characterization methods in the same environment:

  • Pulsed S-Parameters and Pulsed IV networks combined with compact model extraction for an accurate model including Thermal and trap effects.
  • Vector receiver Load Pull combined with harmonic impedance control, time-domain measurements, and behavioural model extraction for first-pass amplifier design.
  • Traditional Scalar Load pull combined with Nano5G tuners for a complete device characterization under modulated signal
  • Stability Analysis software for a robust prediction of power amplifier oscillations and methods to mitigate them.

 


 

IVCAD-Live Visualization

IVCAD includes a live visualization tool for each measurement module. A predefined structure with multiple graphs contains a measurement table section for fast identification of all the measured and calculated parameters. Configurable graphs are also available with full customization of the displayed parameters.
Measurement data can be exported to standard formats like CSV and MDIF.

 


 

IVCAD-Sweep Plan

Automated measurement is an easy task with IVCAD. Sequencing measurements with minimum human intervention is key to optimal testing efficiency. One person can run multiple benches at the same time to speed up testing capabilities. Through drag and drop actions, it is possible to define several tasks to be performed and run the complete measurement scenario automatically.

The “Sweep Plan” takes benefit of all the GUI tools already available in the bench definition interface or from the measurement interface. This way, defining a complete measurement task is possible, without requiring any programming skills, and without any loss of flexibility.
IVCAD automation capabilities using the “Sweep Plan” allow:

  • Single setup and multi-setup configurations
  • Measurement sequencing with loop and stop conditions
  • Nested measurements sweep
  • DUT bias control & optimization
  • Probe station control
  • Chuck temperature control
  • SCPI commands for specific instrument control during the automation
  • Possibility to save sweep plans with all parameters for future use

 


 

IVCAD-Calibration

IVCAD provides corrected data at the DUT reference plane. The correction terms are calculated during the calibration process using a step-by-step wizard. Depending on the setup configuration, different calibrations can be performed in IVCAD:

  • Coaxial Calibration
  • Waveguide Calibration
  • Unsexed Calibration (for On-wafer measurements)
  • Time Domain Calibration

 

In the case of a scalar setup, the calibration procedure is based on power measurements using power meters and signal generators. For vector setups, the Calibration of the Vector Network Analyzer (VNA) is necessary to extract the error terms. Furthermore, depending on the VNA configuration. To minimize the source of errors, IVCAD provides a state-of-the-art calibration wizard that relies on the schematic setup to identify the type of Calibration that is possible to perform and guides the end-user through all the steps, including the validation process to verify and assess the expected accuracy.

 

The auto tuner de-embedding wizard is a unique feature in the VRLP setup in IVCAD that allows the recalculation of the tuner calibration and its related error terms when the tuners' terminations (Source or load) change after the setup calibration. This can happen if we need to change one of the setup components to accommodate the device (switch to higher power handling or wider frequency band components and change a damaged one). The auto de-embedding wizard saves a considerable amount f time and avoids re-calibrating the full system when only a passive device needs to be replaced.

IVCAD Auto De-embedding Calibration


IVCAD-Chronogram

High power devices require measurements in pulsed mode to mitigate thermal effects. Pulsed options often add complexity to settings. Therefore, IVCAD provides a simple user interface for full control of the pulse generators, the receivers, and the trigger signals. Different instruments in the setup can be set with appropriate timings for the pulse setting and pulse measurements. To simplify the task for the end-user, IVCAD embeds a Chronogram that describes, on a time axis, the pulse mode settings, and a configuration panel where all the timing specifications can be set at once.

All instruments in pulsed mode are automatically showing up in the appropriate section of the chronogram: generators (RF signal Generators, DC supplies) and receivers (VNA, Multimeters, Power-Meters)

The measurement windows can be configured for each receiver, and once the chronogram is closed, all the settings are configured automatically in the appropriate instruments.

 


 

IVCAD- DC power supplies control

How to control DC voltage and current?

RF Transistor measurements can be particularly challenging when dealing with DC power supply control. IVCAD allows the DC power supply remote control of up to 6 accesses with associated DC or pulsed voltage and current measurements from the power supplies or using DC precision multimeters and oscilloscopes for pulsed current measurements when the RF signal is pulsed by an RF pulse modulator.
It is very easy to enter various and numerous DC power supply settings for the software GUI without any specific programming skills.

The generation and measurement are set separately for more flexibility. Power ON and OFF sequencing is customizable for DUT protection as well as the timing between each instrument.

How to Calculate a Voltage Drop Across Resistors?

It is a must-have to measure accurate DC voltages at the Device Under Test reference plane (DUT), whatever the current consumption. Because the current can flow through a cable with a parasitic serial resistance or through a shunt resistor for differential current measurements, the voltage drop across the serial or possibly parallel resistors must be taken into account to measure the true voltage at the DUT bias access. A resistive network can be configured into the IVCAD DC power supply user interface to de-embed the measurements and the voltage settings to the DUT reference plane.

 

How to Measure DC or Pulsed Current?

DC current can be measured simply by reading back the DC current from the DC Power supply through remote control. Nevertheless, it is preferable to use precision DC multimeters plugged in series on the DC path when high current measurement accuracy is needed. IVCAD enables a seamless DC setup configuration when DC power supplies and DC voltage and current multimeters are used. An oscilloscope can also be used to measure both DC / Pulsed Voltage and Current. Contact us to check the oscilloscope's drivers, which are available.

 

How to Synchronize Pulse Measurements?

When dealing with complex setups to characterize Transistors in pulsed conditions, it is easy to face the issue of instrument synchronization, especially when using different instruments from different vendors and different generations. For example, some RF sources can generate a fixed output synchronization signal with 50nsec width, but most of the triggered instruments like Power Meters; DMMs… have a minimum trigger hold-off timing of 1usec, resulting in a bad synchronization and wrong measurements, as well as software timeouts.
In this case, it is recommended to advantageously use a Trigger Box with the RF Modulator to help build a robust bench for transistors' Pulsed Characterization.

 


IVCAD-Schematic Editor

IVCAD is turnkey software with a versatile and customizable schematic editor for building a Load pull and Pulsed IV test bench with available laboratory instruments. Depending on the measurements required, different test configurations are possible:

  • I-V Measurements
  • Vector Receiver Load Pull Measurements
  • Traditional Load Pull Measurements
  • Waveguide Vector Receiver Load Pull Measurements

 

 

Devices can be coaxial, waveguide, fixtured or on-wafer.

Each instrument enabled in the setup can be controlled using specific drivers allowing full automation of the measurements. With 15 years of device characterization software development, AMCAD masters instrument controls and provides drivers that optimize the measurement speed without sacrificing accuracy. Each instrument can be set with different options and in different modes.

 

IVCAD Device Characterization is a comprehensive and advanced measurement platform which enables RF & Microwave component characterization, through pulsed IV , S parameters and load pull measurements.

MT930C
Vector Receiver Load Pull

IVCAD MT930C offers a modern and efficient methodology for load-pull measurements. Low-loss couplers, inserted between the tuners and DUT, are connected to a VNA to allow real-time measurement of a and b-waves at the DUT reference plane, enabling vector information not normally made available with traditional setups.

IVCAD measures the real load impedance presented to the DUT without prior assumptions of tuner characterization, positioning, or losses. Extremely accurate transistor’s input impedance derived from the a-and b-waves results in properly-defined true delivered input powerpower added efficiency, and true power gain measurements. Output powers, at fundamental and harmonics, are made available along with multi-tone carrier and intermodulation powers.

Assets of Source Pull for NVNA based load-pull measurements (ARFTG 2012)

 


 

MT930C1
Waveguide Vector Receiver Load Pull

IVCAD MT930C1 is an add-on module for MT930C which enables vector-receiver load-pull measurements using waveguide tuners and waveguide frequency extender modules.

 


 

MT930D1
Traditional Load Pull

Traditional load pull was the first system to automatically measure device performances under various source and load impedances. These test benches are using pre-characterized passive tuners for impedance matching and scalar power detectors for measurements.
Based on the pre-characterization of the impedance tuners, the measurements are relying on the set of measured or interpolated s-parameters of the tuners at different impedance conditions. Raw measurements from scalar instruments (Power meters) are de-embedded, in real time, to the DUT reference plane using the loss calculation of tuners and other components in the setup.

The accuracy of the measurements relies entirely on the quality of the calibration and the mechanical repeatability of the tuners. This load pull architecture is cost-effective.

 


 

MT930D2
Harmonic and Spectrum Add-On

The MT930D2* bench architecture is an upgrade to the MT930D1. It enables harmonic load pull and wideband modulated signal measurements.
Spectrum analyzer (or multiplexer with several power sensors) can be added to read specific power at each frequency as well as power at intermodulation frequencies if driven by a two-tone signal. Depending on the signal source and analyzer, CW, pulsed-CW, single-tone, two tone and/or modulated signals, and their respective measurement parameters, can be achieved. *MT930D1 is pre-required for MT930D2.


 

MT930E
IV Curves

MT930E is a standalone module which enables DC-IV curves for parametric analysis of transistors. The library contains a wide range of drivers for commercial application related instruments. Selecting the DC supplies associated with precision multimeters or SMUs will enable semiconductor parametric analysis in safe operating conditions, using stop conditions given by maximum input and output currents , or maximum DC power compliances.
Start , Stop and Step values can be defined to sweep input voltage or current for different output voltages.

Also, it is possible to sweep the output voltage for different input currents or voltages. For on wafer measurements, IV characterizations can be automated on different transistors using a wafer mapping, through a remote controlled probe station.

 


 

MT930F
CW S-Parameters

MT930F is an add-on module for MT930E which enables S-parameters measurements in CW mode during a DC IV bias point sweep. DC and RF hardware settings are defined in a user-friendly interface where different parameters can be set (frequency sweeps, IF bandwidth, averaging, VNA ports used, VNA calibration files etc.) and saved in one single configuration file for future use. IVCAD supports main commercial VNAs for which it provides robust drivers for each model.

IV measurements and corresponding S-parameters measurements are then recorded into two separate text files. Indexes are used to connect IV measurements and corresponding S-parameters data, insuring an easy access in the visualization tool.

 


 

MT930GA
Time-Domain LSA Add-On

MT930GA is an add-on module for MT930C Vector-Receiver Load Pull which enables time-domain large signal analysis and waveform reconstruction.  When used with supported VNAs and comb generators (harmonic phase references) it does not require any third-party nonlinear VNA software. The LSA add-on records the phase dependency of harmonic content allowing a- and b-waves, voltage and current waveforms plotting as well as dynamic load lines display for each measurement state (impedance/power/bias). All measurements are be de-embedded to the device reference plane.

Time-domain analysis allow the visualization of currents and voltages at the device input and output terminals and help identify DUT’s mode of operation. When used with de-embedding menus, this tool is useful in the study and design of advanced amplifier classes of operation including E, F, J and K and their inverses.

MT930GA can be combined with MT930R1 to easily extract Enhanced Poly- Harmonic Distortion behavioral model (EPHD) with no significant addition of time

Learn More : VNA Based Load Pull Harmonic Measurement De-embedding Dedicated to Waveform Engineering (COMCAS IEEE 2015)

 


 

MT930GB
Keysight NVNA Support Add-On

MT930GB is an add-on module for MT930C Vector-Receiver Load Pull which enables time-domain large signal analysis and waveform reconstruction using Keysight PNA-X network analyzer and its NVNA software.
MT930GB relies on the Keysight NVNA application to measure the phase dependency of harmonic content allowing a- and b-waves, voltage and current waveform plotting as well as dynamic load lines display for each measurement state (impedance/power/bias). Measurements can be de-embedded to the device reference plane. With the appropriate PNA-X options, MT930GB also enables the extraction of X-parameters* or AMCAD EPHD behavioral models.

(* Keysight trademark)

 


 

MT930H
Active Load Pull

MT930H* active load pull module allows the control of ΓL as the ratio between the reflected- and forward-travelling waves at the output of the DUT . A generalized form of the formula can be written as ΓL = (a2/b2). The wave b2 is taken as the wave coming from the device, while a2 is the reflected wave seen by the device under test, coming either from a passive circuit, an active circuit or a combination of both for hybrid load pull.

Active injection load pull relies on external sources (with phase and amplitude control enabled) to inject a signal toward the DUT, thereby creating the appropriate a2 . Because a2 is no longer limited to a fraction of the original reflected signal, external amplifiers may be used to increase the amplitude of a2 so that ΓL can even achieve unity. To the contrary of harmonic passive tuners, a perfect isolation can be achieved between fundamental and harmonic load tuning, which is important when performances are mainly driven by the fundamental load. Finally, IVCAD algorithms enable a great tuning convergence and measurement speed.

*MT930H is an add-on module for MT930C

Learn More on Active & Hybrid Load Pull

 


 

MT930H1
Hybrid-Active Waveguide Load Pull

 

MT930H1 — is an add-on module for MT930H which enables active and hybrid-active load-pull measurements using waveguide tuners and waveguide frequency extender modules

 


 

MT930J
Pulsed IV Curves

MT930J is a stand-alone module for advanced Pulsed IV measurements using dedicated hardware (e.g., AM3200 AMCAD’s Pulsed IV system ). IVCAD enables the visualization of trapping phenomena, gate lag and drain lag, on GaN transistors, but also dynamic self heating on different transistor technologies. The module allows a quasi-instantaneous visualization of pulsed IV characteristics as a function of varying quiescent bias point and temperature of the base plate.

 

Key Features:

  • Pulsed configuration and calibration of all instruments controlled by IVCAD
  • Graphical pulse chronogram easily defines gate, drain, RF source and measurement windows
  • Sweep input or output voltages in linear, adaptive and custom steps
  • IV trace screenshot visualizes IV waveform without the need for an oscilloscope
  • VNA operated in NBW for enhanced accuracy of S-parameters measurements
  • Multiple stop conditions for maximum voltage, current, power and temperature of the DUT
  • Automated probe station control

 

MT930K
Pulsed S-Parameters

MT930K is an add-on module to MT930J which enables synchronized Pulsed S-Parameter measurements in conjunction with Pulsed IV. This option will enable controlling different vector network analyzers. AMCAD recommends to use VNAs equipped with Pulsed S-parameter options to achieve pulsed measurements in asynchronous mode, while insuring a great measurement dynamic range , even with low duty cycles needed to avoid self-heating effects. These conditions are mandatory for model extraction measurements.

MT930K also enables the control of more economic VNAs (without pulsed options) by gating the synchronous RF measurements triggered by the pulsed IV signal.

IV measurements and corresponding measured S-parameter are linked by different indexes for an easy data management in IVCAD visualization tool.

 


 

MT930L
Scripting Language

MT930L scripting tool allows the user to fully customize the measurement sequence and the visualization tools.  Using a library of pre-encoded functions and GUIs used as building blocks by IVCAD, it is possible to automatize a set of measurements with one push button. Used in conjunction with the syntax interpreter and the search engine to find the required functions, the scripting language leverages your IVCAD platform to unrivaled solution in terms of flexibility and powerfulness in semiconductor industry.

Using the script server, customer's external applications can take control of IVCAD through TCP/IP sockets commands to run IVCAD as a slave application. TCP/IP sockets allow programs to talk through a network, but a communication between two programs on the same computer can also be established. This makes the solution ideal when IVCAD has to be part of a pre-established work flow with other software's within the company.

IVCAD Compact Modeling provides an intuitive compact modeling wizard to help extract LDMOS and IIIV transistor models using pulsed IV and pulsed S parameter measurements.

MT930M1
Linear Model Extraction

MT930M1 Linear Model Extraction is used easily to determine the extrinsic (parasitic elements) and intrinsic parameters of III-V and LDMOS transistors. Linear modeling fits measured data to linear model equations and can be automatically optimized or manually tuned to solve for values of the extrinsic (Rg, Lg, Cpg, Rd, Ld, Cpd, Rs, Ls) and intrinsic parameters.

Linear model extraction is a critical first step in the transistor modeling process, any  errors resulting from linear model inaccuracies will prevent the extraction of nonlinear  models. A wizard guides users through a step-by- step process in order to eliminate  user errors and ensure first-pass linear model extraction success. Validation is provided  by comparing intrinsic elements through a multi-bias extraction. Netlist import and export is  available at each level of the linear model extraction process.

AN : Transistor Compact Modeling

 


 

MT930M2A
Nonlinear Model Extraction, III - V

MT930M2A is a nonlinear modeling tool for III-V transistors. It will reuse the extrinsic elements determined by the MT930M1 linear module in order to de-embed the measurement to the transistor’ intrinsic reference planes.

Pulsed S parameters measured with the MT930K module will be used to extract the nonlinear capacitances models through built-in AMCAD’s or user-defined equations. Pulsed IV measurements with the MT930J will be used to extract the nonlinear input diodes and the output current source parameters using AMCAD’s or used-defined equations. Export functionalities and specific templates are then used to upload the model into commercial simulators and include thermal and trapping effects. Finally, the model is refined against VNA based load pull measurements for better approximation of the model in the desired application.

AN : Transistor Compact Modeling

 


 

MT930M2B
Nonlinear Model Extraction, LDMOS

MT930M2B is a nonlinear modeling tool for LDMOS transistors. It will reuse the extrinsic elements determined by the MT930M1 linear module in order to de-embed the measurement to the transistor’ intrinsic reference planes.

Pulsed S parameters will be used to extract different LDMOS nonlinear capacitances models through built-in AMCAD’s or user-defined equations. Pulsed IV measurements will be used to extract specific LDMOS output current source parameters using AMCAD’s or user-defined equations. Export functionalities and specific templates are then used to upload the model into commercial simulators and include thermal effects. Finally, the model is refined against VNA based load pull measurements for better approximation of the model in the desired application.

AN : Transistor Compact Modeling

IVCAD EPHD Modeling is a turnkey black-box modeling solution based on load pull measurements which overcomes the challenge of extracting packaged or on-wafer transistors models in a short time. It enables accurate load pull simulation with commercial harmonic balance simulators.

MT930R1
EPHD Behavioral Model

Need

Extracting a compact transistor model requires several weeks of work, and potentially up to several months when starting from scratch. This investment worth the value when a foundry wants to support all its customers for a large variety of operating conditions (T°; bias, matching conditions).

In this case, the model need to be broadband to cover all the needs.

Nevertheless, there are some cases where such a model is not accurate enough for a particular case, especially for space applications where every point of power added efficiency is crucial.

In this case, the RF transistor model must be perfectly accurate to predict the power added efficient, output power, gain, return loss with a set of harmonic load impedances and for some particular carrier frequencies.

Refining the foundry compact model to make it accurate for those particular operating conditions can be a solution.

Nevertheless, there are some cases where the time needed to extract a compact model is not compatible with the project timeline (one or two weeks maximum) or budget. In this latter case, the EPHD  is the right candidate because it allows extracting a model on the fly from load-pull measurements, which saves considerable design time. The ability of this model to predict the overall design performances without any convergence issues for harmonic balance simulations has been proved even for extrapolated load conditions, during the simulation, and with the load impedances used during the load pull measurement process. Therefore, this new model is a promising candidate for the design of power amplifiers of future telecommunication systems due to its robustness, flexibility, reliability under ROI constraints.

Solution

MT930R1 is a stand-alone module for the extraction of  Enhanced Poly Harmonic Distortion (EPHD) transistor behavioral models.

This tool allows a transistor model extraction on the fly and can advantageously replace load pull measurement data file export in circuit simulators. The EPHD model can be used in Harmonic Balance simulations to describe the transistor behavior as a function of the RF power level as well as fundamental and harmonic terminations.

EPHD model is a proven and robust modeling platform. It can be used for PA circuit design with complex parallel or cascaded branch architectures.

Thanks to use of our  Harmonic Phase Reference, the model extraction is based on IVCAD MT930GA LSA based load pull measurements and does not require time consuming measurement process.

The EPHD can predict the transistor nonlinear behavior against fundamental and harmonic frequencies, for different carrier frequencies, and enables accelerated PA design flow.

 

AN : Behavioral Model of High Power GaN HEMTs for RF Doherty Amplifier

IVCAD can generate an impressive amount of data in a short period of time, thus the visualization module is a powerful tool used to highlight in few steps the key information.

MT930B1
Basic Visualization

IVCAD MT930B1 offers a modern and intuitive visualization package for IV, S-Parameters and Load Pull data.

  • Basic I(V) Viewer plots IV curves of Vd, Vg, Id, Ig and derivatives, as well as time domain data if available.
  • Basic S Parameter Viewer plots S-parameters in standard and custom formats including log magnitude, linear magnitude, phase, polar, Smith Chart…
  • Basic Load Pull Viewer plots impedance sweeps and power sweeps with advanced filtering capabilities

 

Dockable windows allow users to create and save custom IVCAD environments. Templates allow users to save their preferred visualization graphs and recall or share with colleagues. Data Editor allows users to create new parameters based on equations and visualize alongside measurement data. Export allows users to save graphs and plots as JPG or PDF files for reporting. Visualization modules are compatible with IVCAD and common commercial data formats.

 


 

MT930B2
Advanced Visualization Add-On

IVCAD MT930B2 offers a real time post processing visualization capabilities

  • Extended I(V) Viewer allows Dynamic pulsed IV visualization, as a function of time, to check measurement relevance and observe critical data variation such as dynamic self-heating.
  • I(V) wafer Mapping uses I(V) data to observe the spread of DUT DC performances at wafer scale for interpolated parameters.
  • Advanced S Parameter Viewer allows plotting stability, operating and Maximum Gain circles as function of frequency or bias parameters.
  • Extended Load Pull Viewer plots interpolated load pull contours versus power levels; time domain load pull waveforms and, thanks to a patented ‘Magic Source pull’ process, it can dynamically emulate equivalent source pull measurements such as the transistor's transducer gain.

 


 

MT930P
Measurement Toolbox

MT930P is a stand-alone Toolbox module which enables useful post-measurement mathematical tools.

  • IV Tools – compute gm/gd, convert IV data sets, interpolate/extrapolate IV points.
  • S-parameters – TRL fixture extraction, interpolate/extrapolate S-parameters.
  • De-embedding – intrinsic de-embedding of S-parameters and VNA based load pull measurements based on transistor linear model.
  • Converter – mathematical calculator for converting phase, electrical length, power, VSWR, impedance.

 

Designs that lead to unstable MMIC circuits are expensive and extremely time consuming. STAN tool secures your design flow, and reveals hidden circuit instabilities in linear or nonlinear operating conditions.

MT930Q
STAN

STAN tool is a patented solution capable of  assessing the stability of RF & Microwave circuits, which is a critical step in the design flow. In comparison with other methodologies (Rollet & Nyquist Criterion, NDF …), STAN is a unique solution that brings together all the following advantages : FastRigourousUser Friendly, and ready to use with commercial CAD software. The STAN approach calculates a single-input, single-output (SISO) transfer function for a circuit of interest linearized around a given steady state. A simulated frequency response of the linearized circuit is fitted to a rational polynomial transfer function by means of frequency-domain identification algorithm. If no poles on the right-half plane (RHP) are found, it is considered stable.

Key Features:
  • Single-node analysis
  • Multi-node analysis
  • Parametric analysis under variable load impedances
  • Parametric analysis under variable input signal power
  • Monte Carlo analysis
AN : Selecting the circuit’s node with STAN AN : Rollet Factor versus Pole-Zero Identification AN : How to Select the Frequency Range for Analysis ? STAN and the STAN Wizard Installation and Use in AWR (NI) Pole-Zero Identification: Unveiling the Critical Dynamics of Microwave Circuits Beyond Stability Analysis, IEEE Microwave Magazine July 2019 STAN Tool tutorial

Configure your STAN solution



Videos

Transistor Compact modeling and model implementation in MWO
Load pull measurements and transistor model validation
AWR PA design using AMCAD transistor compact model
IVCAD EPHD Behavioral Model
STAN Tool - Experimental example on how to characterize the critical poles of a circuit
STAN Tool - Stability Analysis using Microwave Office from AWR-Cadence