Saturday, May 16, 2020

QUCS Studio vs ADS2016. Annex Simulation. Microstrip Coupled lines


As a Annex of a previous document in this entry you will find a document where it is included one more comparison between the results obtained when a simple coupled pair of microstrip lines are simulated using QUCS Studio and those obtained using ADS 2016.
In the previous document, that you can also find as one entry of this blog, you will find more examples of simulations comparing different microstrip structures very commonly used in high frequency RF circuits.
This time, the schema simulated is a pair of coupled microstrip lines matched in the isolated port and the coupled port with the characteristic impedance, in this case, 50 ohm, then terminated with the MELF component in ADS comparing it with the MOC from QUCS Studio, and, finally, evaluating only the microstrip coupled lines in both simulators.

The link where the Annex can be accesed is the following:


The link where the S2P files with the results obtained from ADS2016 can be obtained in this link:


Sunday, May 3, 2020

Infineon RF Transistors SPICE library converted for QUCS Studio

In the SPICE and Models section of this site, you will find the QUCS Studio compatible models for the RF bipolar transistor library published by INFINEON in their website. The transistors are included in a project and they are the following:

*     BFP181              BFP620F             BFP843              
*     BFP182W             BFP640              BFP843F             
*     BFP183              BFP640ESD           BFQ19S              
*     BFP183W             BFP640F             BFQ790              
*     BFP193              BFP640FESD          BFR106              
*     BFP193W             BFP650              BFR181W             
*     BFP196              BFP720              BFR182              
*     BFP196W             BFP720ESD           BFR182W             
*     BFP405              BFP720F             BFR193F             
*     BFP405F             BFP720FESD          BFR193W             
*     BFP410              BFP740              BFR340F             
*     BFP420              BFP740ESD           BFR35AP             
*     BFP420F             BFP740F             BFR380F             
*     BFP450              BFP740FESD          BFR740L3RH          
*     BFP460              BFP750              BFR840L3RHESD       
*     BFP520              BFP760              BFR843EL3           
*     BFP540              BFP780              BFR92P              
*     BFP540ESD           BFP840ESD           BFR93A              
*     BFP540FESD          BFP840FESD          BFR93AW             
*     BFP620              BFP842ESD

Along with the models test files are included in the project in order to get an idea of what are the shape of the DCDC curves of each transistor.

It is important to note that several models have convergence issues during the DCDC analysis, that are currently under investigation.

Monday, April 13, 2020

Optimizing in QUCS Studio. How to get a package model for a semiconductor device


In the following entry a brief description of how to proceed in order to get the lumped elements model for the package of a certain varicap diode will be presented.
This activity is a need very common in the design process of high frequency circuits. In many occasions the component that is necessary to use in the design is characterized, in terms of its RF performances, only partially, and the rest of the information is not available.
The component that will be characterized in this case is the varactor diode model BB914.
The process of getting a model for a semiconductor device is something far more complex than the quick steps reflected in this entry. But the objective of it is to show that a really more complex what is the characterization of a real component can be carried out using QUCS Studio.

All the files used to make this entry are available in the following link:


A file containing a summary of the process carried out is available in this link:



Tuesday, March 31, 2020

QUCS Studio vs ADS 2016. Performances Comparison


In the following entry of the blog, the comparison between the performance of QUCS Studio, as RF and microwave simulation tool, and ADS 2016 from Keysight, is shown.
It is known, worldwide, that ADS has been the corner stone of the simulation CAD tools, for more than thirty years. It has been, and it will be in the near future, the mirror where all the competitors want of will want to be reflected in.

In order to get an accurate idea of what are the capabilities of QUCS Studio in terms of simulating RF and microwave circuits, the best comparison will be the one that compares the suite with the best ECAD tool available in the market.

Since the most relevant design area that ADS has historically been focused in is the RF and microwave circuits, this will be the type of circuits that will be compared to the equivalent simulated in QUCS Studio.
The document is arranged as a list of microstrip circuit examples, very commonly used in many of the high frequency designs that are analyzed using both CAD tools.
For each example, the main relevant performances are compared. Transmission parameter, reflection parameter mainly.

A brief explanation of the activity is summarized in the following document:  


All the files used in the making of this document are included in the following link, arranged as a QUCS Studio project.




Monday, February 3, 2020

The Angelov MESFET Model built for QUCS Studio


In the present entry, an Angelov MESFET model built for the QUCS Studio CAD tool will be presented.
This model is based in the VERILOG-A built in capabilities that offers QUCS Studio.
The technical background that is necessary to understand the equations and expressions that model the behavior of MESFET transistors can be found, in part, in the following paper:

An Angelov Large Signal Model and its Parameter Extraction Strategy for GaAs HEMT
by
Yan Wang Wenyuan Zhang
Tsinghua University

The paper is available in this link:


The file containing the brief explanation about the process of modelling can be found in this link:


The files that are described in the previous document can be accessed in this link:


Thursday, November 21, 2019

Behavioral models of the basic logic gates based on Verilog AMS.

In a new entry in the section "Verilog AMS Files", they are available for downloading the files that provide the possibility of simulate logic gates, the three basic ones, AND gate, OR gate and the inverter, from the behavioral point of view.

Mixed simulation is not implemented in QUCS Studio. Meaning that it is possible to work with logic circuits, but using the chronogram aproximation. One digital circuit in a QUCS Studio schematic can not be analyzed using transient analysis.

The logic gates coded in Verilog AMS and completed with some lumped elements offer the posibility of simulating using transient analysis with the advantange of the behavioral approximation. The same function for the logic gates implemented using the phisycal model (i. e. building the logic gates with the transistors that compose them physically) will take, on average, more time of analysis.

Wednesday, November 20, 2019

A Voltage Controlled Voltage Source with a Table defined dependency designed in Verilog AMS

As a second part of the post from a few days back, this time it is presented a voltage controlled voltage source with a table defined dependency. In many cases, there are SPICE models that include this type of controlled source as a part of the circuit, and this element, designed basically in Verilog AMS module, allows to cover this type of necesities.

Go and visit the "Verilog AMS Files" section of this site and you will find the links to the documentation and the files that are necessary to run in QUCS Studio this new controlled source.