Using Measurement Expressions in Advanced Design System

Measurement Expressions are equations that are used during simulation post processing. These expressions are entered into the program using the MeasEqn (Measurement Equation) component, available on the Simulation palettes in an Analog/RF Schematic window (such as Simulation-AC or Simulation-Envelope), or from the Controllers palette in a Signal Processing Schematic window.

Many of the more commonly used measurement items are built in, and are found in the palettes of the appropriate simulator components. Common expressions are included as measurements, which makes it easy for beginning users to utilize the system. To make simulation and analyses convenient, all the measurement items, including the built-in items, can be edited to meet specific requirements. Underlying each measurement is a function; the functions themselves are available for modification. Moreover, it is also possible for you to write entirely new measurements and functions.

The measurement items and their underlying expressions are based on Advanced Design System's Application Extension Language (AEL). Consequently, they can serve a dual purpose:

• They can be used on the schematic page, in conjunction with simulations, to process the results of a simulation (this is useful, for example, in defining and reaching optimization goals). Unlike Simulator Expressions, the MeasEqn items are processed after the simulation engine has finishing its task and just before the dataset is written.
• They can be used in the Data Display window to process the results of a dataset that can be displayed graphically. Here the MeasEqn items are used to post-process the data written after simulation is complete.
  In either of the above cases, the same syntax is used. However, some measurements can be used on the schematic page and not the Data Display window, and vice versa. These distinctions will be noted where they occur.

  Note Not all Measurement Expression Functions have an explicit measurement component. These functions can be used by means of the MeasEqn component.

MeasEqn(Measurement Equations Component)

For a complete list of Measurement Functions, refer to the Measurement Expressions in the Advanced Design System.

Symbol

Parameters

Instance Name

Displays name of the MeasEqn component in ADS. You can edit the instance name and place more than one MeasEqn component on the schematic.

Select Parameter

Add	Add an equation to the Select Parameter field.
Cut	Delete an equation from the Select Parameter field.
Paste	Copy an equation that has been cut and place it in the Select Parameter field.

Meas

Enter your equation in this field.

Display parameter on schematic

Displays or hides a selected equation on the ADS schematic.

Component Options

For information on this dialog box, refer to " Editing Component Parameters " in the ADS " Schematic Capture and Layout " documentation.

Notes/Equations

If you are using Advanced Design System, you can place a MeasEqn (Measurement Equation) component in a schematic window. By placing a MeasEqn component on an ADS schematic, you can write an equation that can be evaluated, following a simulation, and displayed in a Data Display window.

Note The if-then-else construct can be used in a MeasEqn component on a schematic. It has the following syntax: A = if ( condition ) then true_expression else false_expression