E8883A Circuit Envelope Simulator

View Full-Sized Image (37 KB) Simulated and Measured performance of a PLL's frequency change with the change in the Divide by N ratio: 1, 1.5, and 4 MHz steps. Using Circuit Envelope, it is possible to simulate and create Time vs. Frequency plots.

E8883A Circuit Envelope Simulator provides an efficient simulation technique for the complex digitally modulated RF signals found in today's wireless circuits. Typical analyses and measurements include: Pseudo-random digitally modulated RF solutions. ACPR, EVM, PAE simulation and optimization. Transient RF solutions. PLL frequency vs. time analysis (lock time). AGC, PLL transient response (ringing, settling, overshoot, etc.) simulation and optimization. High order (5th, 7th, 9th) mixer inter-modulation product analysis. As the first mixed-domain simulator Agilent's Circuit Envelope continues to provide industry-leading innovations that speed simulation and shorten development time. Click on the following links for complete information. Product Information Ordering and Configuration Product Literature Publications User Support

Product Highlights

• New Automatic Verification Modeling capability enables fast co-cimulation with the Ptolemy Data Flow simulator and results in up to a 100 X+ simulation speed improvement with high accuracy. This new feature makes some large-scale verification processes a reality.
  
  Click on the following link for details: Automatic Verification Modeling
  
• Simulates sophisticated modulated signals in high frequency circuits whose characterization was previously impractical or impossible with SPICE or Harmonic Balance
  
• Speeds the design of modern communication circuits based on 2G and 3G technologies such as WCDMA, EDGE, 3GPP, and Wireless LAN
  
• Optimizes circuits in the time-domain for best modulation characteristics, such as VCO frequency settling time
  
• Advanced statistical capability including programmable and swept optimization, Monte Carlo Yield analysis, sensitivity and mismatch analysis, and correlation technique, all with powerful display features and sensitivity histograms.
  
• Characterizes RF feedback loops to aid in the design of phase locked loops and Automatic Gain Control circuits
  
• Efficiently analyzes higher order (3rd, 5th, 7th) mixer intermodulation products and predicts spectral re-growth of amplifiers and mixers
  
• 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 can be very useful in optimization and yield analysis where goals/specs can 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.
  

Product Description

E8883A Circuit Envelope Simulator analyzes today's communication circuits and subsystems and their response to complex, modulated signals.

The simulator analyzes amplifiers, mixers, oscillators, and feedback loops in the presence of modulated or transient high-frequency signals.

View Full-Sized Image (32 KB)
ACPR, Trajectory plot, and EVM measurements are extracted from a Circuit Envelope simulation of a realistic baseband I/Q signal applied to a circuit-level power amplifier.

Circuit Envelope's technology lets you analyze complex RF signals by employing a hybrid time- and frequency domain approach. It samples the modulation envelope (amplitude and phase, or I and Q) of the carrier in the time domain and then calculates the discrete spectrum of the carrier and its harmonics for each envelope time sample.

Thus, the output from the simulator is a time-varying spectrum from which useful information, such as PLL frequency vs time transients, ACPR (adjacent channel power ratio), EVM (error vector magnitude) and NPR (noise power ratio) can be derived.

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.

In Comparison to SPICE

Unlike SPICE, the modulation amplitude and phase of any carrier harmonic is directly accessible for display, or time domain optimization, without the need for intermediate post processing. Where SPICE has to rely on lumped element approximations, Circuit Envelope simulation can include accurate frequency domain models, such as S parameter data, or microstrip discontinuities.

In Comparison to Harmonic Balance

Instead of representing the modulated signals as the sum of Fourier harmonics, as in the Harmonic Balance simulator, Circuit Envelope technology computes the modulation information in the time domain, leaving only the RF carrier and the LO for fast, accurate simulation in the frequency domain.

Circuit Envelope technology is therefore faster than a standard harmonic balance simulation, and also consumes less computer memory. Circuit Envelope more than just highly efficient, it can also analyze RF transient response such as PLL lock times, which Harmonic Balance cannot.

Time Domain Optimization and Statistical Analysis

In addition to simulating the instantaneous amplitude, phase and frequency of any signal harmonic, you can also use the time domain capabilities of ADS to optimize circuit transient performance For example, you can optimize the transient response parameters of AGCs, ACPR, and for the locking time of phase lock loops.

All ADS circuit and system simulators can work in conjunction with ten different optimizers, helping you obtain the best possible performance from your designs. Programmable optimization, swept optimization and other advanced statistical capabilities are some of the new features in ADS. Available statistical methods include Monte Carlo Yield, sensitivity analysis, mismatch analysis and correlation analysis using any kind of distribution. Recent ease of design improvements are automatic normalization and post optimization simulation sequencing. More information can be found at Statistical Design (E8824).

More Information

For more information about circuit envelope simulation, click on the following link:

• How-Siang Yap, Agilent EEsof EDA, Designing to Digital Wireless Specifications Using Circuit Envelope Simulation   (PDF, 229 KB), Applied Microwave & Wireless, June 1998.   Current issue: Applied Microwave & Wireless.
  

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 Automatic Verification Modeling capability enables fast co-simulation.
  
• 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

Product Demos

ONLINE DEMO

Circuit Envelope, Harmonic Balance, Momentum To see a concise online demo of Circuit Envelope, Harmonic Balance, and Momentum simulations in Advanced Design System (ADS), click on the following link: Circuit Envelope, Harmonic Balance, and Momentum Macromedia Flash audio/video. High-speed internet connnection recommended. Complete Online Product Demos

ONLINE DEMO

Range of Simulations To see a concise online demo of the wide range of simulation types that are available in Advanced Design System (ADS), click on the following link: Simulations in ADS Macromedia Flash audio/video. High-speed internet connnection recommended. Complete Online Product Demos

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

Requires the Harmonic Balance Simulator (E8882), the Linear Simulator (E8881), and the Design Environment (E8900).

Product Literature

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

Technical Articles

• How-Siang Yap, Agilent EEsof EDA, Designing to Digital Wireless Specifications Using Circuit Envelope Simulation   (PDF, 229 KB), Applied Microwave & Wireless, June 1998.   Current issue: Applied Microwave & Wireless.
  

Training Classes

Advanced Design System Fundamentals

This is a medium-paced three-day detailed introduction to the application of Advanced Design System (ADS) for communication systems and circuit designs.

This course instructs designers on schematic capture, the proper application of a wide variety of simulators, and the display and manipulation of results.

After a brief study of ADS basic operation, students design and test amplifier and filter circuits that are then placed in a down-converting receiver system for final simulation. Real-world examples are used at all times so that designers can return to their jobs ready to apply ADS effectively to their design challenges.

For detailed course descriptions and class schedules worldwide, click on the following link:

• Agilent EEsof EDA Customer Education

Advanced Topics in Circuit Design

This is a medium-paced two-day course that shows some of the more expert features of Agilent EEsof EDA's Advanced Design System.

This course instructs designers on the proper application of advanced simulation methods found in ADS, use of measured data in ADS simulations, and the modeling of devices used in common design schematics.

Some of the advanced simulation methods used in the course are transient-assisted harmonic balance, yield optimization, oscillator analysis, design of experiments (DOE), and sensitivity analysis. Very realistic circuits are used in this course, such as those found in cellular phones or radio receiver sections. At the end of this course, the designer should be very comfortable with using ADS and understand how to implement the more advanced simulation methods on their own designs.

For detailed course descriptions and class schedules worldwide, click on the following link:

• Agilent EEsof EDA Customer Education

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