The waveform window is able to display analog simulation output. This simulation output comes from external simulators (such as Spice). When the system is asked to display the results of an external simulation, it reads the simulation output and shows it.

The analog waveform window looks like the picture below. Note that there is a side bar with a cell explorer in the window, just like in all windows, but the explorer has a "SIGNALS" section that lists the signals found in the simulation (and optionally a "SWEEPS" section if swept data was found). When reading HSpice data, the signals and sweeps sections may be further qualified by analysis, for example "TRANS SIGNALS", "DC SWEEPS", etc.

### Wave Panels

The waveform window contains a set of panels, each with one or more signals and waveforms. In a panel, signal names are shown on the left, and their waveform on the right. Above the signal names in each panel are 5 names and controls:

- Panel number each panel is numbered so that it can be hidden and retrieved.
- Close (an "X") to remove the panel from the waveform window.
- Hide to stop displaying the panel, but keep it available (it can be restored by selecting its name from the popup at the top of the waveform window).
- Remove Signal remove the selected signal from the panel (the DELETE key works for this, too).
- Remove All Signals remove all signals from the panel.

You can select a signal by selecting either its name or the actual waveform. Note that when you click on a signal, the equivalent network in the associated schematic or layout window is also highlighted. If a Spice deck was generated from the schematic, then crossprobing its simulation results to layout may not work properly. This can be fixed with the Run NCC for Schematic Cross-Probing command (in menu Tool / NCC, see Section 9-7-2).

You can change the color of a signal by right-clicking on its name and choosing a different color.

You can rearrange the order of the waveform panels by clicking on their panel-number and dragging the panel to a new location. You can move signals from one panel to another by dragging their names to their desired panel. If you use shift-click to drag signals, they are copied to the new panel.

You can add signals to the list by double-clicking on their name in the "SIGNALS" area (or by dragging those names to the waveform part on the right). The signals will be added to the highlighted panel (the one with the bold vertical axis). You can create a new panel, with no signals in it, by clicking on the button in the upper-left of the waveform window ().

If the layout or schematics cell that produced the simulation is being displayed in another window, and the currently selected network in that window is found in the simulation output, then that output can be added to the waveform window with the Add to Waveform in New Panel command (in menu Edit / Selection). The command Add to Waveform in Current Panel overlays the signal on top of others in the currently selected waveform panel.

The order of signals in the waveform window is saved in the original cell so that subsequent simulations will show the same signals. You can also save the configuration of the waveform window with the Save Waveform Window Configuration to Disk... command (in menu Window / Waveform Window) and you can restore the configuration with the Restore Waveform Window Configuration from Disk... command. The Export Simulation Data... command (in menu Window / Waveform Window) writes a tab-separated file with all simulation data (names and values). This is useful for doing spreadsheet analysis of the data.

### Sweeps

If the simulation had sweeps, those values are shown in the cell explorer in the "SWEEPS" area. You can right-click on a sweep and choose to include or exclude it from the display (double-clicking on the sweep toggles its inclusion). Right-clicking on the "SWEEPS" icon lets you include or exclude all of them.

A single sweep can be highlighted to distinguish it on the display. Right-click on that sweep and choose "Highlight". To remove all highlighting, right-click on the "SWEEPS" icon and choose "Remove Highlighting".

### Time Control

Two vertical cursors appear in the window, called "main" and "extension" (the extension cursor is dotted). Their time values and their difference are shown at the top of the window. You can click over the cursors and drag them to different time locations. You can also use the "Center" buttons to bring these cursors to the center of the display.

| Another way to measure in the waveform window is to use the "measure" tool (see Section 4-7-4). This tool lets you drag a rectangle, and it shows the left/right time with difference as well as the top/bottom values with difference. The tool snaps to data points so it is easy to get precise measurements.

The time axis of the simulation window can be controlled with the appropriate Window menu commands. Use Zoom Out and Zoom In to scale the time axis by a factor of two. Use Focus on Highlighted (in menu Window / Special Zoom) to display the range between the main and extension cursors.

| Besides controlling time with menu commands, you can also use the Pan and Zoom tools of the toolbar. |

The pan tool lets you smoothly shift time when you click and drag. In the zoom tool, you zoom into an area by clicking and dragging out that area. To zoom out, shift-click in the center of the desired area.

You can control the horizontal and vertical range precisely by double-clicking in the vertical scale area. The dialog lets you type exact values into the ranges. |

Both the horizontal and vertical axis are drawn linearly. Either axis can be changed to a logarithmic scale by right-clicking on the ruler and choosing "Logarithmic" (use "Linear" to restore the scale).

The different panels in the waveform window are locked in time: they all show the same range of time, as shown at the top of the waveform window. If you click on the "time lock" button at the top of the waveform window (looks like a lock with the time on it: ) then time is unlocked, and each panel has its own time scale. Now individual panels can show a different range of time than the rest.

A set of VCR buttons is available to animate the main time cursor. The play rate can be controlled by the up-arrow and down-arrow buttons to the right of the VCR controls. These buttons make the playback run faster or slower. As the time cursor sweeps across the waveform window, the original circuit can be seen to change levels.

These window functions apply to the analog simulation windows:

- Window / Fill Window make all data fit in window.
- Window / Zoom Out show twice as much time.
- Window / Zoom In show half as much time.
- Window / Special Zoom / Focus on Highlighted show from main to extension cursors.
- Window / Pan Left show earlier time.
- Window / Pan Right show later time.
- "Pan" tool in tool bar freehand drag of time.
- "Zoom" tool in tool bar drag area to zoom in, hold shift to zoom out.
- "Measure" tool in tool bar for measuring time.

### Eye Plots

The horizontal axis does not have to represent time. Any signal can be used in the horizontal axis, simply by dragging that signal onto the horizontal ruler. To restore the horizontal axis to show time, right-click on it and choose "Make the X axis show Time".

### Other Controls

At the top of the waveform window, above the signal names, are many useful controls. Those relating to time have already been discussed. Here are the remaining buttons:

- "Refresh" Rereads the simulation output file and updates the display. If the simulation has been re-run, and the output file is different, then this button shows the new data. This function is also available with the Refresh Simulation Data command (in menu Window / Waveform Window).
- "Show Vertices" Controls the display of dots on the vertices of the waveforms. The button toggles between three states: (1) showing lines only, (2) showing lines and dots, and (3) showing dots only.
- "Show Grid" Displays a grid in the waveform panels. The button toggles between showing and not-showing the grid.
- The Panel popup This is a list of all panels, including the hidden ones. Selecting a panel from this list toggles its "hidden" state, making a visible one disappear, and making a hidden one reappear.
- "Grow" and "Shrink" These buttons, which show a waveform being stretched or squeezed, cause the minimum panel size to change. By shrinking the panel size, more of them can fit in the window without having to use a slider to access them. Also, the panels can be resized individually by dragging any of the dividers.