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Kit Operation
6.12.1 ADC Highpass Filters
The ADC of the TLV320AIC33 can have a high-pass filter enabled, which helps to reduce the effects of
DC offsets in the system. This function is enabled as shown in
Figure 13 . The four options for this setting
are disabled, or three different corner frequencies which are based on the ADC sample rate.
Figure 13. ADC Highpass Filter Settings
6.12.2 Enabling Filters
The de-emphasis and effect filters (the biquad filters) of the TLV320AIC33 are selected using the
checkboxes shown in
Figure 14 . The De-emphasis filters are described in the TLV320AIC33 datasheet,
and their coefficients may be changed (see Section 6.12.7 ).
Figure 14. Enabling Filters
When designing filters for use with TLV320AIC33, 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
TLV320AIC33 until the Download Coefficients button is pressed. To avoid noise during the update of
coefficients, it is recommended that you uncheck the Effect Filter enable checkboxes before downloading
coefficients. Once the desired coefficients are in the TLV320AIC33, enable the Effect Filters by checking
the boxes again.
6.12.3 Shelf Filters
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 15 , 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.
SBAU114 – November 2005 TLV320AIC33EVM and TLV320AIC33EVM-PDK User's Guide 23