National Semiconductor is proud to present these models that are provided to aid in the PLL design process. These models can greatly accelerate the design process and aid in the understanding of PLL behavior. Although these tools do simulate results, it should be understood that the only true guarantee is that which is listed in the datasheet.

Miscellaneous PLL Models (382 KB)
This is a collection of various PLL models for loop filter design and simulation. Many of these require Mathcad 7.0 to run. To use this resource, run this self- extracting zip file and put the contents into a folder. Run models.pdf and click on the appropriate link to run the model of your choice. The concepts in most of the models are described in the PLL book that is on wireless.national.com.

These older offline tools are superseeded by EasyPLL available on wireless.national.com

Windows Loop Filter Design (3 MB)
This is a windows loop filter design program that performs loop filter design and analysis. A bode plot is generated. For this program, the user enters the comparison frequency, loop bandwidth, added attenuation, phase margin, charge pump gain, VCO gain, and N counter value in order to instantly calculate the loop filter.

EasyPLL Ver 1.6 (271 KB)
This program performs prescaler checks, part selection, design and simulation (including lock time and phase noise). It does not use windows. This is a self-extracting zip file. For this program, the user specifies the crystal reference, comparison freqency, and output frequency range. From this prescalers, PLLs, and VCOs are considered. Then the loop filter is designed and simulated.