E8881A Linear Simulator

Product Highlights

• Microstrip, stripline, finline, and coplanar waveguide models.
  
  For a complete list of ADS models, click on the following link: Circuit Models
  
• Includes Model Composer, a unique, patented, EM-based modeling method, which provides EM accuracy and generality at circuit simulation speed. Model types include standard interconnect components such as opens, stubs, bends, crosses, and tees on custom substrates.
  
• User-defined linear models and output equations can be created, enhancing design flexibility.
  
• Generalized noise analysis with temperature
  
• Back-annotation of the DC solution at each node, directly onto the schematic, without having to re-simulate.
  
• Advanced circuit optimization with programmable and swept optimization for maximizing circuit performance.
  
• Monte Carlo analysis to predict manufacturing yield prior to production.
  
• Powerful data display commands allow the creation of many useful statistical plots and histograms.
  
• Symbolically-Defined Device (SDD) and Frequency-Defined Device (FDD) models to allow simulation of both large and small= signal behaviors for nonlinear devices and high-level circuit blocks, such as mixers and amplifiers without having to write C code.
  
• Platform Computing Load Sharing Facility (LSF) supports the following options:
  
  • Find the fastest available server and run.
    
  • Run simultaneous simulations.
    
  • Distributed Processing. Most efficient for sweeps that don't require the solution of the previous run.
    

• Variable Equations (VAREQN) variables may now be referenced in Measurement equations (MEASEQN) and Optimization/Yield/DOE (Design of Experiments) controllers.
  
• Measurement equations can access the contents of any existing dataset. This feature is very useful in optimization and yield analysis where goals/specs make direct reference to existing data. The data may be generated from a previous simulation, or from an external source, such as another simulator, or an instrument.Includes Microwave Transistor Library, RF Transistor Library, High Frequency Diode Library, Analog Parts Library, RF Passive SMT Library, Murata SMT Library and RF Systems Library.
  
• Advanced statistical design capability aids in optimizing performance and production yield. Features include automatic normalization of sensitivity analysis output and optional run of final analysis after optimization run completion. For more information see Statistical Design (E8824)
  

Product Description

E8881A Linear Frequency Domain Circuit Simulator is used to analyze and optimize RF and microwave circuits (for example, amplifiers, oscillators, couplers, filters, and matching networks) that operate under linear conditions.

The technology can be applied to the design of any passive and small-signal active circuits used in wireless, RF, microwave, surveillance, radar, and other communication applications.

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When a schematic of the circuit has been created, the linear simulator allows you to check the topology automatically for unconnected pins and wires. The simulator then performs all necessary linear measurements such as S-, Z-, Y-, and H-parameters, circuit impedance and admittance, reflection coefficients and VSWR, gain, loss, noise, unilateral gain, noise figure, input/output noise temperature, group delay, stability factor, stability measure, and noise gain stability circles. In addition, the simulator can perform Swept Parameter Analysis, such as noise figure versus a change in a component value.

The simulator's extensive passive and small signal active device model libraries include many of the parts needed for the high frequency designs, including improved multi-layer coupled line element models. The simulator also can perform linear analysis with nonlinear models at user-defined DC bias. A parametric sub-networking feature allows for customization and the incorporation of any existing sub-network from another design.

For a complete list of ADS models, click on the following link: Circuit Models

Convergence

Recent improvements in the DC solution include two new algorithms that allow large circuits with singular matrices to converge. Problems with circuits of singular matrices can be either topological or numerical (large diversity in the circuit element values). For topological problems, a new algorithm detects these conditions and adds the appropriate circuit approximation for a subset of the problem topologies. For numerical problems, a new algorithm detects and fixes any numerical problems that could lead to formulating a singular matrix.

Statistical Design

This simulator includes many statistical tools that provide designers with a new design process. The tools utilize automated Optimization, Monte Carlo yield analysis, Sensitivity analysis, correlation analysis on any kind of distribution, and the ability to do statistical analysis with hierarchical mismatch models. Powerful data display commands allow the creation of many useful statistical plots and histograms.

The Monte Carlo yield analysis method predicts yield by simulating a manufacturing process in which the units (for example, amplifiers, mixers) produced have randomly varying component values. This helps to identify which components in your design require tighter control. The pass/fail status of any component is determined comparing the simulated performance to the actual requirement of the design. Yield is then defined as the percentage of units passed.

The enhanced Optimization Output Controller now includes new and highly advanced optimization methods, including programmable optimization and swept optimization. Recent ease of design improvements are automatic normalization and post optimization simulation sequencing. More information can be found at Statistical Design (E8824).

Model Composer

Model Composer enables you to create multi-dimensional, parameterized models for passive planar components. The unique, patented modeling method is EM-based, providing EM accuracy and generality at circuit simulation speed. Model types include standard interconnect components such as opens, stubs, bends, and tees on custom substrates.

The generated models are fully compatible within Advanced Design System and include both schematic and layout representation, as well as a complete electrical model. Components can be created in libraries, logical groupings, or sets of components.

User-Defined Models

A Symbolically Defined Device (SDD) and a Frequency Defined Device (FDD) allow you to create a user-defined model by specifying, on the circuit schematic, algebraic relationships among the port variables without having to write source code.

SPICE Model Generator

The SPICE Model Generator lets you convert a frequency-domain S-parameter characterization into a model that SPICE can use. The S-parameters can come from the Advanced Design System frequency domain simulator, a High Frequency Structure Simulator, Momentum, or an actual network analyzer measurement.

The model generator develops a netlist, containing a sub-network, which represents the modeled structure. This enables the generation of SPICE models from S-parameter data and improves the speed of your work flow. For design flexibility, models can be created with four different design topologies:

• Ideal transmission line topology
• N-section ladder network
• Lumped Pi topology
• Rational polynomial representation (HSpice or ApSim Spice formats)

The first three models are low frequency extractions from S-parameter data. The fourth model uses curve fitting to frequency data. The first three models are applied when the frequency data points in the S-parameter data file are free of noise. If the S-parameter data is taken from a network analyzer, noise may be present in the low frequencies and the rational polynomial representation should be applied.

The SPICE model generator also allows for full chip verification in the SPICE simulator after completion of the RF design in Advanced Design System.

Recent Product Enhancements

Product enhancements in recent releases include the following:

• Major improvement in simulation processing speed when using design kits with a large number of symbolic expressions in their model cards.
  
• New Hybrid (Random / Gradient) Optimizer that is capable of more quickly finding the global minimum.
  
• Optimization Goal Normalization improvement on two or more goals. As a result, the final optimized results are more optimum and accurate.
  
• A new Statistical Design Histogram Function with one automatically built-in equation that provides measurement histograms or Sensitivity Histograms after any statistical Monte Carlo run.
  

ADS Models

For a complete list of ADS models, click on the following link: Circuit Models

How To Buy

To request immediate sales assistance - for help choosing the best system; for product configuration and integration details; to request telephone assistance or an on-site demo of the software; or to request a price quotation - click on the following link:

• Agilent EEsof EDA Sales Assistance

Configuration Details

Required

• E8900A Design Environment

Product Literature

• Advanced Design System (PDF, 4.0 MB).
  12-page color brochure. 4 March 2005.

Technical Articles

• Mounir Adada, ADS 2001 Delivers Ease-of-Use andGreater Capabilities for MMIC Design, Microwave Product Digest, September 2001.   PDF Version (138 KB).   Current issue: Microwave Product Digest.
  
• Mounir Adada, Best of Both Worlds: New Modeling Technology Combines EM Accuracy With the Speed of Analytical Models, Microwave Product Digest, December 2001.   PDF Version   (PDF file, 175 KB).   Current issue: Microwave Product Digest.
  

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