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Philip F. Dindo, Herzberg Institute of Astrophysics,
National Research Council Canada, Victoria, BC, Canada
"Interactive Interdigital Filter Design Using MMICAD Software",
Microwave Journal, January 2003.
This article describes the design of interdigital microstrip filters using the MMICAD Linear Simulator. Interdigital microstrip filters with tapped-line input are compact structures suitable for microwave integrated circuits. Their advantages include low levels of spurious second harmonic passbands and relatively low cost. This article shows how MMICAD can be used for the full filter design cycle, encompassing specification, basic equations, parameter calculations, simulation and optimization. The final design is verified using the Sonnet electromagnetic simulator.
J. Wareberg and D. Kennedy, Optotek Ltd., Kanata, Ontario, Canada
S. Schmidt, LPKF Laser and Electronics, Wilsonville, OR
"Design and Prototyping of a Transimpedance Front-end Amplifier for
Dense Wavelength Division Multiplexing Circuits",
Microwave Journal, September 2001.
As part of the development of an optical power monitor for use in dense wavelength division multiplexing (DWDM) circuits, the effectiveness of a logarithmic operational amplifier transimpedance front-end amplifier was investigated, and the performance of this design compared with a switched gain, linear, transimpedance amplifier (TIA) front-end. The circuit was prototyped using the combination of the MMICAD LAYOUT™ software and the LPKF C60 PCB prototyping machine.
Philip Dindo, David Kennedy, and James Wareberg,
"Software Simplifies Large-Signal Transistor Modeling",
Microwaves & RF, October 1999.
Model generation is an essential part of any computer-aided-engineering (CAE) system. Large-signal models are particularly important for studying the inherent nonlinear behavior of semiconductor devices and semiconductor-based active component designs. The LASIMO (large-signal modeling) software developed by Optotek eases the task of creating and modifying metal-semiconductor field-effect-transistor (MESFET) and high-electron-mobility-transistor (HEMT) models for nonlinear computer simulation.
Philip Dindo, Randall North, and David Kennedy,
"Extract MESFET Models for Wireless Applications",
Microwaves & RF, June 1998.
Accurate small-signal transistor models are required for precise simulation of circuits for wireless applications. Although the designer can use the scattering parameters of the active device, equivalent circuit models offer size-scaling and portability advantages. In addition, bias-dependent, small-signal models provide useful insight into circuit behavior
Ce-Jun Wei, Yevgeniy A. Tkachenko, Dylan Bartle,
Philip Dindo and David Kennedy, "
"A Compact Large-Signal Model of a GaAs MESFET",
Microwave Journal, December 1997.
A comprehensive GaAs MESFET large-signal model is presented in this article to account for charge conservation and dispersion and self-heating effects. An improved set of capacitance and charge equations is used for consistent small and large-signal nonlinear simulations. Transconductance and output conductance dispersion is modeled by combining a feedback network and subcircuit, which describe the self-heating effect. Model parameter extraction is performed using a newly developed user-defined model extraction module within the commercial LASIMOTM simulator. The new model accurately predicts the IV, CV, bias-dependent S-parameter; waveform, power and linearity characteristics of the MESFET.
Philip Dindo, Roman Meierer and Randall North,
"Computer-Aided Design of MMIC Variable Attenuators",
Microwave Journal, November 1997.
Variable attenuators are used widely in telecommunications and electronic warfare applications to adjust the signal level or compensate for intrinsic gain variations in operating temperature. This article discusses the design, fabrication and testing of a 3 to 7 GHz, voltage-controlled MMIC attenuator and demonstrates the circuit simulation, test equipment control and data-acquisition capabilities of the MMICADTM Suite of computer-aided engineering (CAE) and computer-aided test (CAT) software. In this application, MMICAD's user-defined modeling feature is key to achieving a satisfactory design.
Philip Dindo, David Kennedy, Neil Lefebvre and Randall
North,
"CAE Software Aids Design of L-Band MMIC LNA",
Microwaves & RF, May 1997.
Computer-aided-engineering (CAE) software tools can speed and simplify the design of passive and active high-frequency circuits, including amplifiers. As an example, the MMICAD linear simulator and MMICAD LAYOUT module, part of the MMICAD software suite from Optotek Ltd (Kanata, Ontario, Canada), were used to design and lay out an L-band amplifier for fabrication with a gallium arsenide (GaAs) monolithic-microwave-integrated-circuit (MMIC) process. Running on a standard personal computer (PC), these CAE tools can avoid costly design iterations and help speed time to market.
Randy North, David Kennedy and Mike Murphy,
"Database Sampling - A Real World Solution to MMIC Yield Sensitivity
Analysis",
Microwave Journal, April 1997.
In the course of a typical MMIC development and manufacturing program, there are a number of common issues which affect design success as it relates to manufacturability. Even when specific designs are considered successful (in the sense that working MMICs are fabricated), the circuit and wafer yields must be improved to make system insertion affordable. To improve yields, the designer can go through the necessary steps of process and device enhancements to improve device performance. However, process development is long term in nature, expensive, and any results must be validated prior to production. There is much to be gained by applying CAE techniques to enhance circuit and wafer yields thereby compensating for the influence of the statistical foundry process variation.
By applying the unique combination of active device yield simulation through "Database Sampling" and passive element yield simulation through statistical modeling, we can address important yield issues and reduce their impact dramatically. The approach is discussed in context of the manufacture of a 1.6 GHz LNA MMIC; however, the techniques explained are widely applicable for MMIC design at all frequencies.
Dominic FitzPatrick, Randy North and Neil Lefebvre,
"Filter Design and Manufacture Using the MMICAD Software Suite",
Wireless Design and Development, March 1997.
The pressures of product development have led to extensive effort being put into design tools to reduce the time taken to simulate prototypes and evaluate new circuits. This article demonstrates the use of the new MMICAD Suite from Optotek Ltd. to improve design cycle efficiency. The use of MMICAD Suite components and the time saving capabilities of the MMICAD Version 2 simulator are demonstrated in application to the design and manufacture of high quality lumped and distributed filters at frequencies of 70 MHZ, 770 MHZ, and 8150 MHz.
Dominic FitzPatrick, Randy North and Neil Lefebvre,
"Software Suite Improves Design-Cycle Efficiency",
Microwaves & RF, September 1996.
Computer-aided engineering (CAE) has made tremendous strides in recent years, from humble "software slide rules" to sophisticated modeling tools that can predict the behavior of complex circuits. With Version 2.0 (for Windows) of the MMICAD personal-computer (PC) linear circuit simulator from Optotek Ltd. (Ontario, Canada) as well as its optional synthesis and layout modules, engineers can perform quick circuit design and layout then directly drive a milling machine for an instant prototype.
Dominic FitzPatrick,
"Simulating Interactions Between RF Stages",
Microwave Engineering Europe, May 1996.
The advent of low cost integrated system components such as MMIC (Microwave Monolithic Integrated Circuits) devices and ceramic filters has greatly eased the creation of complex subsystems. However, these circuit blocks can interact and the performance of the whole cannot just be assumed to be the sum of the parts. Using the parameter variation function of the MMICAD linear simulation software, a receiver frontend for the band 1800 to 1900MHz, consisting of low noise amplifier, filter and MMIC variable attenuator is analyzed and the interaction and the system performance as a whole is observed.
