One method is to use the NCO Compiler MegaWizard^{®} Plug-In Manager to approximate the phase increment value. On page 2 of the NCO Compiler MegaWizard Plug-In, you will find the Frequency Calculator. Enter the input clock period and the desired output frequency and click **Calculate**. The Frequency Calculator will display the approximate phase increment value in the MegaWizard interface.

The other method to obtain the phase increment value is to use the following equation:

F(output_of_sinusoid) = [Phase_increment/(2^{N})] * F(clk) where: F(output_of_sinusoid) = Desired output frequency of the NCO Compiler, N = Accumulator bit width, and F(clk) = Input clock frequency

When selecting which method to use, you should note that the Frequency Calculator in the MegaWizard Plug-In Manager can introduce rounding errors when calculating the phase increment value. Therefore, Altera recommends that you use the equation method of calculating the phase increment value for better accuracy.