Amplifier QuickStart Guide

The Amplifier QuickStart Guide is intended to help you get started using the Amplifier DesignGuide effectively. For detailed reference information, refer to subsequent chapters of this manual.
The Amplifier DesignGuide includes many useful simulation setups and data displays for amplifier design. The simulation setups are categorized by the type of simulation desired and the type of model available. Most of the simulation setups are for analysis, but there are some for synthesizing impedance matching networks. The DesignGuide is not a complete solution for amplifier designers, but provides some useful tools. Following are some feature highlights.

• Simulations of eight high-efficiency power amplifier examples
• A detailed section on statistical design
• For most data displays, the equations are visible on an Equations screen within each data display file, to make it much easier to see what is being calculated and how to modify it if necessary.

Note This manual is written describing and showing access through the cascading menu preference. If you are running the program through the selection dialog box method, the appearance and interface will be slightly different.

Using DesignGuides

All DesignGuides can be accessed in the Schematic window through either cascading menus or dialog boxes. You can configure your preferred method in the Advanced Design System Main window. Select the DesignGuide menu.
The commands in this menu are as follows:

• DesignGuide Studio Documentation > Developer Studio Documentation is only available on this menu if you have installed the DesignGuide Developer Studio. It brings up the DesignGuide Developer Studio documentation. Another way to access the Developer Studio documentation is by selecting Help > Topics and Index > DesignGuides > DesignGuide Developer Studio (from any ADS program window).
• DesignGuide Developer Studio > Start DesignGuide Studio is only available on this menu if you have installed the DesignGuide Developer Studio. It launches the initial Developer Studio dialog box.
• Add DesignGuide brings up a directory browser in which you can add a DesignGuide to your installation. This is primarily intended for use with DesignGuides that are custom-built through the Developer Studio.
• List/Remove DesignGuide brings up a list of your installed DesignGuides. Select any that you would like to uninstall and choose the Remove button.
• Preferences brings up a dialog box that allows you to:
  • Disable the DesignGuide menu commands (all except Preferences) in the Main window by unchecking this box. In the Schematic and Layout windows, the complete DesignGuide menu and all of its commands will be removed if this box is unchecked.
  • Select your preferred interface method (cascading menus vs. dialog boxes).

Close and restart the program for your preference changes to take effect.

Note On PC systems, Windows resource issues might limit the use of cascading menus. When multiple windows are open, your system could become destabilized. Thus the dialog box menu style might be best for these situations.

Accessing the Documentation

To access the documentation for the DesignGuide, select either of the following:

• DesignGuide > Amplifier > Amplifier DesignGuide Documentation (from ADS Schematic window)
• Help > Topics and Index > DesignGuides > Amplifier (from any ADS program window)

Basic Procedures

The features and content of the Amplifier DesignGuide are accessible from the DesignGuide menu found in any Advanced Design System Schematic window, as shown here

The eight menu selections from DC and Bias Point Simulations through Lumped Multi-Element Z-Y Matching Networks are for selecting various simulation setups and amplifier examples. These are further categorized, as explained in subsequent sections of this document.

Each of the eight menu selections from DC and Bias Point Simulations to Lumped Multi-Element Z-Y Matching Networks have additional selections. The menu for schematics for DC and bias point simulations appears as follows.

Selecting one of these menu items, such as BJT I-V Curves..., copies a schematic into your current project that is set up for generating a bipolar junction transistor's current-versus-voltage curves.
The BJT I-V curve schematic appears as follows.

Each schematic has a sample device that has already been simulated. The simulated results are displayed in a data display file that opens automatically after the schematic is copied into your project. Modify the BJT by editing its model, or delete the device and replace it with a different one. The red boxes enclose parameters you should set, such as the range of base currents and the range of collector voltages. After making modifications, run a simulation and the data display will update.

Note All schematics have a sample device and/or model, or a sample amplifier. The data display that opens after you make a menu selection has pre-simulated data from the device or amplifier. You must replace the device or amplifier on the schematic and run a new simulation. The data display will be updated with the new data.

Following are the results of the simulation.

Most of the information on this data display and on others in the DesignGuide is in a format that engineers can easily understand.

Tips

• We have minimized the visibility of equations that you should not need to modify. They are included in a separate Equations page.
• Information about items on a data display that you would want to modify is enclosed in red boxes.
• Many of the data displays have multiple pages. Those that do have a note indicating what information is on other pages.

If, after selecting a DesignGuide menu command that has inserted a schematic and opened a data display, you re-name the schematic and then run a simulation, the most efficient way to display the results is to open the data display file that corresponded to the original schematic, and update the default dataset name (which is usually the same as the new name of your schematic), to display your latest simulation results.

Selecting the Appropriate Simulation Type

The Amplifier DesignGuide is divided into eight categories for different simulation types. Your design objective and the type of models you have available will determine which menu selections you select first.

DC and Bias Point Simulations

If you have a Nonlinear FET or BJT model available, you can start with DC and Bias Point Simulations, as shown here.

These selections can be used to determine data such as the following:

• I-V curves of a device
• Approximate class A output power and optimal bias point
• Gm, fmax, and ft versus bias
• Noise figure and S-parameters versus bias
• Optimal source and load impedances for maximum gain or minimum noise figure, versus bias

Note While this DesignGuide is targeted to power amplifier designers, many of the schematics and data displays are quite useful for small-signal or low-noise amplifier designers as well.

S-Parameter Simulations

If you have only S-parameters (possibly with noise data) available, or want to simulate an amplifier's small-signal performance, start with S-Parameter Simulations, as shown here.

These can be used to determine data such as the following:

• Noise figure and NFmin, maximum available gain, and S-parameters
• Optimal source and load impedances to attain the minimum noise figure or maximum gain
• Feedback network element values to attain stability
• Noise and available gain circles
• Stability circles and stability factors
• Stability and S-parameters versus power (actually these require a nonlinear model.)
• Group Delay

Nonlinear Simulations

If you have a nonlinear device model available and want the optimal source and load impedances at the fundamental frequency (to maximize output power and/or power-added efficiency), use Load-Pull or Source-Pull schematics in 1-Tone Nonlinear Simulations, as shown here.

If you have a nonlinear device model available and want the optimal source and load impedances at the fundamental frequency (to maximize output power and/or power-added efficiency, or minimize third- or fifth-order intermodulation distortion), use Load-Pull or Source-Pull schematics in 2-Tone Nonlinear Simulations, as shown here.

If you have a nonlinear device model available and want the optimal source and load impedances at the fundamental and harmonic frequencies (to maximize output power and/or power-added efficiency), use the Harmonic Impedance Opt or Harmonic Gamma Opt schematics in 1-Tone Nonlinear Simulations, as shown here.

The difference between the two optimizations is that in one case, you specify the ranges of allowed real and imaginary impedances, and in the other, you specify the allowed reflection coefficients as circular regions on the Smith Chart.

If you have a nonlinear device model available and want the optimal source and load impedances at the fundamental and harmonic frequencies (to maximize output power and/or power-added efficiency, and minimize intermodulation distortion), use the Harmonic Impedance Optimization or Harmonic Gamma Optimization schematics in 2-Tone Nonlinear Simulation, as shown here.

Again, the difference between the two optimizations is that in one case, you specify the ranges of allowed real and imaginary impedances, and in the other case you specify the allowed reflection coefficients as circular regions on the Smith Chart.

If you already have an amplifier design, and you want to characterize the nonlinear performance over frequency, power, and other swept parameters, select the appropriate schematic from 1-Tone Nonlinear Simulations, as shown here.

The selections for 2-Tone Nonlinear Simulation follow.

There are several high-efficiency power amplifier examples. Simulations of these can be accessed under Power Amplifier Examples - By Class of Operation. Included are Class AB through Class F, with Doherty and Class S examples as well.

Amplifier statistical design is also available. These schematics and data displays, which describe steps you may take to minimize performance variation and maximize yield, can be accessed under Amplifier Statistical Design.

If you want to generate an arbitrary impedance or admittance, or match to a device's equivalent input or output circuit, using ideal, lumped elements only, use one of the schematics under Lumped 2-Element Z and Y Matching Network, as shown here.

Lumped, multi-element matching networks can also be used, as shown here.

Note The Passive Circuit DesignGuide includes impedance matching capabilities.

Tools

These utilities provide added functionality to this DesignGuide. They can be seen in the following figure. A brief description is provided for each below. For more information select the help button in the individual utility.

Transistor Bias Utility

The Transistor Bias Utility provides SmartComponents and automated-assistants for the design and simulation of common resistive and active transistor bias networks. The automated capabilities can determine the transistor DC parameters, design an appropriate network to achieve a given bias point, and simulate and display the achieved performance. All SmartComponents can be modified when selected. You simply select a SmartComponent and with little effort redesign or verify their performance.

Smith Chart Utility

This DesignGuide Utility provides full smith chart capabilities, synthesis of matching networks, allowing impedance matching and plotting of constant Gain/Q/VSWR/Noise circles. This guide assumes you have installed the associated DesignGuide with appropriate licensing codewords.

Impedance Matching Utility

The Impedance Matching Utility performs the synthesis of lumped and distributed impedance matching networks based on provided specifications. The Utility features automatic simulation, sensitivity analysis, and display setup to enable simple and efficient component verification.