Spectrum Software
Industrial Strength Simulation




Spectrum Software has released Micro-Cap 11, the eleventh generation of our SPICE circuit simulator.

For users of previous Micro-Cap versions, check out the new features available in the latest version. For those of you who are new to Micro-Cap, take our features tour to see what Micro-Cap has to offer.






Micro-Cap 11 can encrypt not just macros, but library files as well. Most commercial modeling is done in the form of subcircuits which are saved in text files. Here, for example, is a portion of the analog.lib provided by Spectrum Software as a part of the Analog Libraries:

Unencrypted library file

The file is not encrypted. You can see the contents and create a circuit diagram of the models. If you are a semiconductor manufacturer and these models describe what you feel is proprietary to your company, you might want to encrypt them to protect your intellectual property. Here is how you would go about encrypting the file.

1) Load the file using the File Load command.

2) Select the File menu Encrypt / Decrypt option. That invokes the Encryption dialog box. It looks like this:

Encrypt / Decrypt dialog box

To encrypt the file simply enter a password. Enter it again to be sure that the password you want to use is entered. Click on the OK button. Micro-Cap encrypts the critical portions, leaving the headers intact. This is done so that you can see the pin names and any possible parameters used by the subcircuits. The encrypted file is saved to disk. It looks like this:

Encrypted file

The critical parts of the subcircuit have been encrypted leaving the comments and the .subckt line intact. That way you can see the pin names (which are needed when the part is entered into the Component library) and parameters (which are needed when you place the part in a schematic), and the comments (which are helpful in understanding the pin functions and parameters).

When Micro-Cap analyzes a schematic containing an encrypted part, it decrypts it and parses the contents as it would for an un-encrypted part. The contents just never get displayed.

To decrypt a library file, load it, then select the Encrypt / Decrypt item from the File menu. Enter the password. Click OK. The program decrypts the entire file, saves it to disk, and displays the file in pain text.

Macros are handled somewhat differently because it is necessary for the user to be able to view partially encrypted library files but not so with encrypted macro files.

To encrypt a macro, do this:

1) Load the macro file using the File Load command.

2) Select the File menu Encrypt / Decrypt option.

3) Enter the desired password twice.

4) Click on the OK button.

The program encrypts the macro file, saves it to disk, and removes the file from memory. If you subsequently load the file, the program will ask for the password. If you enter the password correctly, the program displays the file. It does NOT save the decrypted file to disk. To do that you must use the File menu Save or Save As command.

To decrypt an encrypted macro file do this:

1) Load the macro file using the File Load command.

2) Enter the password.

3) Optionally use the Save command to save the decrypted file to disk.

Download Summer 2014 Circuit Files
Return to the main Newsletter page