Multirate CIC Design Express VI

Digital Filter Design VIs and Functions

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Multirate CIC Design Express VI

Owning Palette: Multirate Filter Design VIs

Installed With: Digital Filter Design Toolkit

Creates a cascaded integrator comb (CIC) filter.

Dialog Box Options
Block Diagram Outputs
 Place on the block diagram  Find on the Functions palette

Dialog Box Options

ParameterDescription
Magnitude ResponseContains the plot of the magnitude response. You can drag the cursors in the plot to change the specifications.
  • Magnitude in dB—Specifies whether this Express VI uses decibels or a linear scale to express the magnitude response. If you place a checkmark in the checkbox, this Express VI converts a linear magnitude response to decibels. This Express VI uses decibels by default.
  • Passband—Specifies the color of the lines in the magnitude plot that represent the passband response and the passband edge frequency. The default is blue.
  • Maximum aliasing frequency—Specifies the color of the lines in the magnitude plot that represent the aliasing distortion and the maximum aliasing frequency. The default is red. This option is available only if you set Filter type to Decimation or No Rate Change.
  • Maximum imaging frequency—Specifies the color of the lines in the magnitude plot that represent the images and the maximum image frequency. The default is red. This option is available only if you set Filter type to Interpolation.
Main SettingsContains the following options:
  • Filter type—Specifies the type of CIC filter that this VI creates. The valid values include No Rate Change, Interpolation, and Decimation. The default is Decimation.
  • Number of stages—Specifies the number of stages in the CIC filter. The valid range is [1, 8]. The default is 4.
  • Filter factor—Specifies the sampling frequency conversion factor of the CIC filter. If you set Filter type to No Rate Change, the value of this input must be an integer greater than or equal to 1. If you set Filter type to Interpolation or Decimation, the value of this input must be an integer greater than or equal to 2. The default is 2.
  • Differential delay—Specifies the number of null values in the frequency response. Increasing the value of the differential delay increases the number of null values and the sharpness of the transition band in the frequency response. A larger differential delay value also requires more hardware resources. The valid values include 1 and 2. The default is 1.
  • Input sampling frequency—Specifies the sampling frequency, in hertz, of an input signal for the CIC filter. This input must contain a value greater than zero. The default is 1 Hz.
Analysis SettingsContains the following options:
  • Analyze CIC filter—Specifies if you want to analyze the passband distortion and aliasing distortion for the CIC filter.
  • Passband frequency—Specifies the passband frequency of the CIC filter. This input is available only if you place a checkmark in the Analyze CIC filter checkbox. This Express VI calculates the default value as 80% of fN/4. If you set Filter type to Interpolation or No Rate Change, fN is the Nyquist frequency of the input sampling frequency. If you set Filter type to Decimation, fN is the Nyquist frequency of the output sampling frequency .
  • Passband distortion—Returns the magnitude distortion at the passband frequency in a unit that the Magnitude in dB option determines. This output displays the magnitude distortion value only if you place a checkmark in the Analyze CIC filter checkbox.
  • Aliasing distortion—Returns the magnitude distortion at the maximum aliasing frequency in a unit that the Magnitude in dB option determines. This output displays the magnitude distortion value only if you place a checkmark in the Analyze CIC filter checkbox.

Block Diagram Outputs

ParameterDescription
CIC filter outReturns the new CIC multirate filter.
error outDescribes the error status that this VI or function produces.
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