Electronic-design-automation (EDA) software is a starting point for many high-frequency design engineers. Modern EDA tools can predict the performance of an RF/microwave component or circuit to within a fraction of a decibel but, like any software package, they must be relatively easy to use. In developing the next version of the popular Advanced Design System (ADS) suite of design tools, the design engineers and software developers at Agilent Technologies' Esof EDA Division recognized the need to combine improved circuit-design productivity with increased ease of use. The result is Agilent's ADS 2004A software, one of the most intuitive yet powerful releases of this well-known design suite.
The ADS software suite has long been recognized as an industry-leading design package for RF/microwave circuits. In all fields of product development, and particularly in software development, there is often a tension between making a tool powerful and making it easy to use.Creating a simple user interface in itself is no great engineering feat. The challenge lies in maintaining the engineering power of a complex platform like ADS under the control and access of a simple user interface.
The latest version of ADS, Release 2004A, contains enhancements to its power and flexibility, but focuses on improving the ease-of-use for the most common design tasks, and providing an easier, more efficient design flow.
In EDA software, a key aspect of usability is the speed or responsiveness of the whole process. The user may not notice great improvements in linear simulation if the resulting data display time is increased, for example. Thus, this release of ADS focuses on the entire linear simulation process, from "simulation button down to data display up." The amount of overall improvement will vary according to the particular computer platform running ADS (see table), with complex circuits in general showing the greatest speed benefits and Windows XP personal computers (PCs) enjoying the greatest overall increase in simulation speed. Customers involved in the beta release frequently commented, "The overall product feels very responsive."
This latest release of ADS includes major enhancements to the tuning function. Again, speed improvement is an important usability factor. The 5 to 15 speed improvement provided by ADS 2004A results in true real-time tuning of circuits. The company offers an on-line demonstration of the ADS2004A's new features including this improved tuning speed at the link www.agilent.com/find/eesof-ads2004a-demo, while Fig. 1 shows enhancements to the user interface that simplify the tuning function.
ADS 2004A offers a new feature for snapping to a selectable step size while tuning. Tuning a circuit where the values of components can be varied with high resolution adds insight but yields impractical values. Setting the step size of a component's value and then snapping to these values when tuning improves the manufacturability of the circuit.
The tuning process was carefully considered when developing ADS 2004A. Improvements to the tuning interface deliver added functionality, such as making optimization parameters tunable with a single button click, and enhancements in the schematic window and data display improve productivity for the entire process. In addition to clicking on a component to make it tunable while the tuning interface is active, a component's tuning parameters (minimum, maximum, and step-size values) can be defined and saved on the schematic itself for improved efficiency. Adding legends to data display plots and displaying the values of the tuned components with each memory trace simplifies documenting and tracking the effects of a component value on a circuit's performance.
A major enhancement to the ADS user interface is the addition of a greeting dialog and schematic wizard. Wizards are often included in consumer software to simplify common tasks. In ADS 2004A, the greeting dialog (Fig. 2) is automatically displayed when ADS is launched, giving quick access to projects and a link to the quick start manual. To set up a simulation in any EDA software, the designer is faced with a variety of questions concerning what type of circuit, whether or not it will include subcircuits, what type of simulation is needed, what sweep parameters are needed, and how the design should be set up on the schematic page. The new schematic wizard in ADS 2004A simplifies this process with a series of simple questions, resulting in a simulation-ready schematic and a sample circuit with which to get started (Fig. 3).
The new schematic wizard guides designers through simulation setup by allowing designers to first choose the circuit type by application. Linear circuits, active device characterization, amplifiers, mixers, oscillators, and other application circuit choices are provided for setting up the simulation. Next, a list of sample circuits is provided or designers can choose an existing design. Finally, designers choose the sweep type, and the resulting schematic, complete with simulation and sample circuit, is displayed. The beauty of the wizard is that it preserves all of the power and flexibility of ADS, while simplifying the common steps involved in setting up a schematic for simulation.
Usability, while the highlight of this ADS release, is accompanied by a number of other enhancements:
- RF System Budgeta new frequency-domain-based system analysis tool that finds the component or subsystem that limits the performance of a design.
- Simulation improvements include automation of transient-assisted harmonic-balance simulations; improved phase-noise analysis that provides a single, accurate result; faster Krylov solver times when simulating oscillators; and improvements in memory management for more effective simulation of larger circuits when using the Direct Harmonic Balance simulator.
- A new physical connectivity engine that allows users to establish electrical interconnections based on polygonal-shaped layout artwork. The engine can extract interconnection information on the fly.
- Linux operating system support (RH 7.2, 7.3, and 8.0).
- New Wireless Test Benches provide linked sources and measurements for predefined wireless tests in ADS and the RF Design Environment software platform (from within the Cadence environment).
- Improved accuracy of the thick-metal models in the Momentum electromagnetic (EM) simulator.
- A new ultrawideband orthogonal-frequency-division-multiplex (UWB-OFDM) DesignGuide.
- An improved AgilentHBT transistor model, with self-heating effects.
- An improved Amplifier Behavioral Model, which includes multidimensional data for modeling under various temperature or bias conditions.
- A new Advanced Communications Model Set, which provides new Ptolemy, models for WLAN 802.11, WMAN 802.16, and UWB-OFDM.
- A new IBIS utility enables import of IBIS models for signal-integrity applications.
- Industry standard PC Installation.
- An improved Mixer2 RF system-level mixer model includes nonlinearity and noise characteristics.
- A new HSDPA-coded uplink source and base-station receiver supports bit-error-rate (BER) simulations.
The enhancements to ADS 2004A benefit new, occasional, and power users alike, by providing ease-of-use along with the depth needed to productively accomplish challenging design tasks. Agilent is encouraging customers to view the improvements in ADS 2004A by offering the chance to enter a weekly drawing for a combination 256M memory stick/mp3 player to anyone who views the demo available at www.agilent.com/find/eesof-ads2004a-demo. Agilent Technologies, Inc., EEsof EDA Div., 1400 Fountaingrove Pkwy., Santa Rosa, CA 95403; (707) 577-4680, FAX: (707) 577-4620, Internet:www.agilent.com/find/eesof.