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4.11.3

Digital Effects Filters

4.11.3.1

Shelf Filters

TLV320AIC3104EVM Software

The digital effect filters (the biquad filters) of the TLV320AIC3104 are selected using the check boxes

shown in Figure 20. The De-emphasis filters are described in the TLV320AIC3104 data sheet, and their

coefficients may be changed (see Figure 18).

Figure 20. Enabling Filters

When designing filters for use with TLV320AIC3104, 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 TLV320AIC3104 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 TLV320AIC3104, 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 21, 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 21. Shelf Filters

To use these filters, enter the gain desired and the corner frequency. Choose the mode to use (Bass or

Treble); the response will be plotted on the Effect Filter Response graph.

TLV320AIC3104EVM and TLV320AIC3104EVM-PDK

SLAU218 – August 2007

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