What is the advantage of staying on Silver Maintenance Support?
	"Data" models based on S2P files seem a very costeffective solution. What justifies the use of an equivalent circuit model?
	Ansoft Designer error when loading Modelithics libraries "Specified library cannot be found"
	Can I perform statistic simulations using the Part Value input parameter in CLR library models?
	Does Modelithics only handle packaged devices?
	For some models in the CLR library, why is the predicted Qfactor different from what is published in the vendor data sheets?
	How can the "Global" part-value scalable models in the CLR library be accurate if the parasitics vary from part to part, and even in a nonmonotonic fashion?
	How do changes in metallization thickness in the substrate definition affect Modelithics Global Model performance?
	How do Modelithics transistor models differ from what I can download from the vendor website?
	I am using a 59mil FR4 substrate in my design. Some of the models I am using from the CLR library report a warning during simulation that the valid substrate thickness has been exceeded. Is the model still valid, and how can I tell?
	I observe a nonmonotonic variation in the predicted resonant frequency when I sweep the part value in some of the CLR models what is the explanation for this?
	If the Modelithics part models the "component-to-substrate" characteristics and EMbased layout simulations model the "pad and trace" within the overall EM structure, does the effect of the "pad-to-substrate" get duplicated when using Microwave Office?
	In looking at Modelithics measured and modeled resonance behavior vs. frequency for series capacitors, the first self resonance tends to shift up in frequency, as the substrate thickness becomes thinner everything else held constant . What is the explanation for why the resonant frequency increases with decreasing H ?
	Receive ADS Error:"Cannot load component symbol" when I select a component symbol.
	Some vendors suggest that their models are "pad stack independent," and provide suggested ways to incorporate custom pad stack effects into the models they provide. Why are Modelithics models provided with fixed pad stack dimensions?
	What is meant by the term Modelithics Global Model™?
	What kinds of transistor models can Modelithics extract?
	When I run an Sparameter simulation on ADS using models from the Modelithics CLR library, I get an Agilent License Error.

A:

The advantage to keeping maintenance for our models really comes into play as the simulators release new versions of their software. If for some reason their upgrades change the way our models work then we would be available to work with their technicians and resolve the issues. Additionally, if there are upgrades to your models you would receive them.

Examples of model updates we have implemented to models, include adding pad removal to all our CLR Library models and pad scaling to some of them. Periodically we re-characterize and update the models. Staying on support will make sure you can always get the latest model available and transfer your license to a different computer if needed (for customers with node locked or servers license).

Platinum Maintenance applies to complete library installations, in which case you also keep getting all the new models added to the libraries you purchased.

A:In some cases, the use of S-parameter data is a good solution that provides results with sufficient accuracy. However, there are many good arguments for using equivalent circuit models, including: the ability to perform statistical analyses Monte Carlo simulations, the fact that equivalent circuit models will always be accurate at DC whereas extrapolation errors can occur when using S2P files below, and above, the frequency range of the data file, and the ability to accurately predict Q-factor. Two very important advantages of Modelithics` Global Models are the ability to perform continuous part-value optimization which generally converges more quickly than when using discrete partvalue optimization and the ability to retain accuracy on a wide range of substrate types. It is also useful to consider that the time and expense needed to to set up measurements of one surface mount part is about the same as the cost to purchase a fully-documented, part and substrate-scalable model from Modelithics!

A:In order to access the models in the Modelithics libraries, the libraries (including the Components, Symbols, Footprints and Padstacks) must be configured for each Designer project and circuit design. The libraries are configured from the Tools > Configure Libraries pop-up window. Select "User Libraries" and then find the Modelithics library inside C:\Program Files\Ansoft\Designer2\userlib\Modelithics. Note that you can specify the library configuration as the default setup for all subsequent circuit designs within a given project by clicking on the Save as Default box.

A:For statistical simulations Monte Carlo, Yield, etc the Tolerance parameter should be used, and NOT the Part Value parameter. The nominal value for the Tolerance parameter should always be equal to 1; statistics should be attached to this parameter as *percentage* variations around the nominal part value. This information can generally be obtained from the component vendor. If the statistics are instead attached to the Part Value parameter itself then all parasitic elements of the model will vary along with the nominal element capacitance, inductance or resistance depending on the model and this may introduce excessive performance variation into the simulation. In general the parasitic and higher order effects do not scale in direct proportion to the nominal element value and more realistic predictions are typically obtained by applying statistical distributions to only the nominal element. Note that the simulator will not issue warnings if statistics are attached to the nominal part value as the internal code has no way of detecting this.

A:Modelithics can handle on wafer, chip and wire, as well as packaged devices on a variety of mounting or circuitboard interfacing environments.

A:The Qfactor in vendor data sheets is calculated from measurements made with the part mounted in a specific test fixture or sometimes from expected trends in part performance. When a part is mounted on a board, the substraterelated parasitics affect the overall impedance, which in turn change the calculated Qfactor. Fairly significant Qfactor reduction can be observed just due to the loss of an FR4 PCB beneath the part, particularly for low-loss components. The effective series resistance included in the CLR library models is based on measurements made by Modelithics using either a Boonton resonant coaxial line or an RF impedance analyzer.

A:Modelithics Global part-value scalable models are extracted from measurement data and the variation of the equivalent circuit parameters—including all parasitics—is therefore characterized in a very accurate way. The resulting Global Models have been developed specifically to capture the variation in parasitics from part-to-part, even if that variation is nonmonotonic.

A:It affects the Zo and beta calculation for the solder pad models, which are treated like microstrip sections. This parameter, combined with the height from the ground affects the effective series inductance (ESL), for example, in ESL, in capacitor models. The effects are usually small except for very thin substrates (5 mil and below).

A:

Vendor models vary in format and quality from no model at all or a poor model, to very good models. In general the available models have little or no documentation and are often represented with what today we might consider to be a relatively simple model. In most cases test fixture information is either missing or a standardized coaxial fixture of some form has been used (in the case of a packaged device), which may or may not represent how the device will behave in the circuit design environment of the target application.

It is Modelithics business to provide and support high accuracy and well-documented models that are convenient to use and tailored to designers needs. In doing so, we partner with component & IC vendors as well as microwave simulation software and test equipment providers. Each Modelithics model is carefully developed using the latest modeling techniques and each is well documented with details about the test fixtures used, reference planes and measurement-to-model agreement among other aspects relevant to designers. Many of the available models are “substrate-scalable,” They are intended to augment the information available from vendors and they are also sold, leased and supported in the form of our “NLT” non-linear transistor library. for ADS and AWR Microwave office. We can also provide NLT models in Ansoft designer, Cadence PSPICE, Cadence Spectre RF and Genesys on demand. Some of these models are also substrate scalable and/or temperature scalable. For an example NLT Library model data sheet – please see

A:Each model in the Modelithics CLR library is developed using measurements from a set of substrates that span a range of thickness and/or dielectric constant. This information is provided with each model`s data sheets. The substrates used for characterization in turn define a range of substrate height-to-dielectric constant ratio over which the model is validated. However, if for a given model the thickest substrate used was 31mil FR4, this does not necessarily mean the model is inaccurate on a thicker substrate. Generally the substraterelated parasitics diminish rather quickly for substrate thickness greater than about 30mil. You can test the variation versus thickness by performing a parameter sweep in your circuit schematic—if the response for the model in question is basically stable on the thicker substrate than the model is still accurate. Much more care is needed when using substrates that are thinner than those used for model development, as the substrate related parasitics increase as the SMD gets closer to the ground plane.

A:Surface mount components often demonstrate nonmonotonic variation of the resonant frequency as a function of the part value. Consider the example of a chip inductor: when increasing the part value a manufacturer may change the wire length, diameter, spacing, and winding pattern. It is thus possible for the interwinding capacitance to decrease while the inductance increases from one part to the next, and the resonant frequency may therefore increase with increasing part value. Although less common, similar effects can happen with chip capacitors as plate number, spacing, and overlap are modified to change the nominal capacitance value. Being measurement-based, Modelithics CLR models will accurately predict resonant frequency variation versus part value. However, a user must be aware of the upper frequency limit for which a given model has been validated; beyond this upper frequency the prediction of resonant frequency cannot be guaranteed to be accurate. In some cases, the trend in resonant frequency versus part value may also vary non-monotonically at part values that do not correspond to actual vendor part numbers.

A:It is our position that the pad effects are best modeled using the Modelithics models, primarily because the end effects beneath the part will not be the same with and without a part soldered in place. Our models are based on measurements of this actual environment including the component/pad interaction, while the planar simulator will not take things into account in the same way. The recommended approach is to terminate the input feedline with a stepinwidth that is appropriate to match the dimensions of the feedline to that of the pad stack, and place the separation between EM simulation and circuit simulation at that point. Having this occur in an automated fashion can be simulator specific, as is the translation from a schematic to a layout. In some cases, the simulator will connect the pad stack edges to the edge of a feedline as one might expect while layout translation may move the center of the pad stack to the edge of a feedline. We are discussing similar issues with the EDA vendors, to try to determine the most user-friendly and transparent solution. Again, our suggested approach is to exclude the pads from the EM simulation and always to include steps-in-width as necessary.

A:A simplified circuit model for a surface mount capacitor is a series RLC with two shunt C`s pi network. In a 2-port configuration the frequency at which ImZin = 0 increases as the shunt capacitance increases. The frequency also increases as the series L decreases. Both effects occur as the substrate height decreases. In the RLC-shunt C pi-network the classical "resonance" where the impedance is real goes away as the shunt capacitance increases, so its more correct to refer to it as the S11 minimum. Also if the shunt capacitance starts to get relatively large larger than we typically see for surface mount RLCs the S11 minimum may decrease with decreasing substrate height

A:The Modelithics models are designed to run with ADS versions 2002C and later. This error usually results if you are using an earlier version of ADS.

A:When an SMD is soldered to a pad stack on a PCB, a coupled system is formed comprised of the part, the pads and the substrate. It is our experience that pad stack effects cannot be removed from SMD models in a generic and accurate way. For example, if 20 different capacitors from the same family are mounted to identical pad stacks, there is not one representation of the pad stack effects that can be de-embedded from all the capacitor models. {Modelithics is currently investigating a modification of the model format in which the pad stack geometry will be variable. In the meantime, you can contact Modelithics with specific questions, and custom models with your pad dimensions can be provided.}

A:A Modelithics Global Model is a specific method of using a single model to represent an entire range of surface mount components on a wide variety of substrate materials. Since a single model represents every available value for a specific component, that object can be used in optimization routines that choose the best value to satisfy your design objectives. The second unique feature of Global Models is that they can be applied to most substrate materials. Simply specify the substrate thickness and dielectric constant, and the model will accurately emulate the component on the specific material chosen for your design.

A:Generally speaking, Modelithics can extract the wide range of models available in Agilent`s ICCAP software for MOSFETS, MESFETs, HEMTs, BJTs and HBTs, plus other models not yet addressed by ICCAP. This includes models such as Curtice, EEHEMT, and Angelov for FETs/HEMTs, and GummelPoon and VBIC for BJTs/HBTs. Custom models are also developed depending on your project requirements

A:The error that may occur looks like this:

Agilent License Error
x No such feature exists
Feature: sim_envelope
License path: .......
FLEXlm error: 5,357

The Sparameter simulation runs properly, however. The error message you get is not due to a problem with the model itself, but rather with some of the security features in ADS.

The Modelithics CLR library models include a User Compiled Model UCM. When a UCM is used, since it can run in a variety of simulations i.e. DC, AC, Envelope and/or Harmonic Balance, the licensing software checks for those licenses sim_syslinear, sim_linear, sim_harmonic, sim_envelope, sim_transient to be available. The error message you get regarding envelope is due to that license check, and not because an envelope simulation is or may be used in your design.

To suppress this message, go into the file:
/config/hpeesof.cfg

Find a line that reads:
AGLMERR = off

Change this to read:
AGLMERR = sim_envelope

This line is used to suppress errors associated with license checks if a license error pops up, but then the simulation completes, that`s license check error.