Datasheet

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6.7.1 Enabling Filters
6.7.2 Shelf Filters
Kit Operation
The right-hand side of this tab shows a display that plots the magnitude and phase response of each
biquad section, plus the combined responses of the two biquad sections. The coefficients used for the
plotted responses are shown below the graph for both Biquad 1 and Biquad 2. Note that the plot shows
only the responses of the effect filters, not the combined response of those filter along with the
de-emphasis filters.
The de-emphasis and effect filters (the biquad filters) of the TLV320DAC32 are selected using the check
boxes shown in Figure 5 . The De-emphasis filters are described in the TLV320DAC32 data sheet, and
their coefficients may be changed (see Section 6.7.6 ).
Figure 5. Enabling Filters
When designing filters for use with TLV320DAC32, the software allows for several different filter types to
be used. These options are shown on a tab control in the lower left corner of the screen. When a filter
type is selected, and suitable input parameters defined, the response will be shown in the Effect Filter
Response graph. Regardless of the setting for enabling the Effect Filter, the filter coefficients are not
loaded into the TLV320DAC32 until the Download Coefficients button is pressed. To avoid noise during
the update of coefficients, it is recommended that the user uncheck the Effect Filter enable check boxes
before downloading coefficients. Once the desired coefficients are in the TLV320DAC32, enable the Effect
Filters by checking the boxes again.
A shelf filter is a simple filter that applies a gain (positive or negative) to frequencies above or below a
certain corner frequency. As shown in Figure 6 , in Bass mode a shelf filter applies a gain to frequencies
below the corner frequency; in Treble mode the gain is applied to frequencies above the corner frequency.
Figure 6. Shelf Filters
14 TLV320DAC32EVM and TLV320DAC32EVM-PDK SLAU201 – November 2006
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