IVCAD 3.8

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 characterzation, positioning or losses. Extremely accurate transistor’s input impedance derived from the a- and b-waves results in properly-defined true delivered input power,  power 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)

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.

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 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 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 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 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 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

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 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 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.

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 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 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

MT930R1 is a stand-alone module for the extraction of  Enhanced PolyHarmonic 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. 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.

The model extraction is using on MT930GA LSA based load pull measurements and does not require time consuming measurements process.

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

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.

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 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.

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 : Fast, Rigourous, User 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

Non-Foster Impedance Matching For Electrically Small Antennas (Stan Used In Chapter 3)