Flattened Sweep & Cross Section Markers

010_flattened_sweep_cross_section : Flattened Sweep & Cross Section Markers

Requires: SmartSpice & Smartview

Minimum Versions: SmartSpice 4.18.16.R and SmartView 2.32.5.R

This example demonstrates crossover compensation and output impedance characterization of an Audio Power Amplifier circuit (reference "J. Puhan, T. Tuma, I. Fajfar, SPICE for Windows 95/98/NT, Electrotechnical Review, Ljubljana Slovenia, vol. 65, no. 5, page 267-271, 1998"). The example illustrates the techniques used to generate Figures 2, 3, and 5 of Puhan et al. using built-in SmartSpice and SmartView features.

Important SmartSpice and SmartView features demonstrated in this example include the following:

  • Automatically generating a RAW file to store the simulation results (.OPTIONS POST).
  • Using PARAMETRIC_DATA_IN_RAW to store .PARAM values as the parameter is varied with SWEEP.
  • Enabling FLATTENED_SWEEP for Cross Section Marker calculations in SmartView.

The input deck for Figure 2 and 3, a common netlist, and the model files are used to characterize crossover compensation (.DC analysis for Figure 2) and measure Output Impedance versus Frequency (.AC analysis with .LET calculation for Figure 3) at a few, pre-selected input offset voltages (Vbias). The CROSSOVER COMPENSATION and OUTPUT IMPEDANCE versus FREQUENCY results demonstrate these concepts.

The input deck for Figure 5is used to characterize and measure Output Impedance versus Frequency (.AC analysis with .LET calculation) at many input offset voltages (Vbias).

As noted in Puhan et al., when the number of data points specified in the SWEEP becomes large, visual analysis can become manually cumbersome. By enabling FLATTENED_SWEEP and PARAMETRIC_DATA_IN_RAW from the .CONTROL block, these multiple variations in offset voltage are flattened into a single vector for each Vbias step. The single, flattened vector becomes much easier to manipulate and work with in the SmartView application.

The flattened OUTPUT IMPEDANCE versus FREQUENCY result demonstrates this SmartSpice feature.

By using SmartView to open the RAW file produced by Figure 5 input deck's simulation, a Cross Section Marker is placed at 1KHz . Clicking the "Calculate" button in the Cross Section Marker pop-up window generates the OUTPUT IMPEDANCE versus INPUT OFFSET (Vbias) result (Figure 5 of Puhan et al.). Detailed instructions for generating the Cross Section Marker plot are outlined in the Figure 5 input deck.