Continued from Photodiode Amplifier Design using Photodiode Wizard - CN-0312 Example
Photodiode Wizard enables a designer to quickly verify results in SPICE, using auto-generated SPICE simulation files included in the downloaded design package.
The CN-0312 example used in the previous post will be used for illustrative purposes.
Step 1: Get Design Files
At any point in the Photodiode Wizard design process, the designer can download .zip file containing several design files, including SPICE files and a design report.
Click "Get Design Files" and within a few minutes, the designer will receive an e-mail with a link to download the design package. (Get Design Files feature will require being logged into MyAnalog)
The .zip file contains (among other files and folders) a folder named "Spice Files," with the following contents:
- ACAnalysis.cir
- NoiseAnalysis.cir
- TransientAnalysis.cir
Photodiode Wizard-generated .cir netlists are text-based SPICE files with information about circuit components, connections, values, etc. The files also contain information about the circuit analysis - type (AC, transient, noise, etc), frequency/time range, etc.
And example netlist is illustrated below. For more information about text-based netlist syntax, see Berkeley's SPICE Page.
Step 2: Running simulations using .cir files
The included .cir files can be simulated using a variety of SPICE simulation engines, but I'll be using ADIsimPE for illustrative purposes.
Open ADIsimPE, and locate the Command Shell window. Select Simulator -> Run Netlist...
In the open window, select the .cir file you want to simulate, and click Open
(ACAnalysis.cir is used in this example)
Return to the Command Shell window. Select Graphs and Data -> Add Curve...
In the Define Curve window, click the down arrow in the Available Vectors drop down. Select "OUT" and click OK.
(For noise analysis, select "onoise")
Step 3: Comparing SPICE results to Photodiode Wizard results
ACAnalysis.cir vs. Photodiode Frequency Response view (click images to enlarge):
TransientAnalysis.cir vs. Photodiode Step Response view (click images to enlarge):
NoiseAnalysis.cir vs. Photodiode Noise Gain view (click images to enlarge):
In the Define Curve window, type onoise/inoise in the Expression - Y field to plot the noise gain
Measuring Total Noise in SPICE, and comparing to total noise reported in Photodiode Wizard
Run simulation for NoiseAnalysis.cir. In Command Shell, select Graphs and Data -> Add Curve. In Available vector drop down field, select onoise.
In the plot window, check the box next to onoise. Then select Measure -> A More Functions...
In the Define Measurement window, select Total Noise, and click OK
SPICE measurement vs. Photodiode Wizard results:
I encourage you to post any questions regarding Photodiode Wizard, as well other circuit design-related questions to Engineer Zone.