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Kit Operation
6.10.1
ADC Highpass Filters
The ADC of the TLV320AIC32 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 10
. The four options for this setting
are disabled, or three different corner frequencies which are based on the ADC sample rate.
Figure 10. ADC Highpass Filter Settings
6.10.2
Enabling Filters
The de-emphasis and effect filters (the biquad filters) of the TLV320AIC32 are selected using the
checkboxes shown in
Figure 11
. The De-emphasis filters are described in the
TLV320AIC32
datasheet,
and their coefficients may be changed (see
Section 6.10.7
).
Figure 11. Enabling Filters
When designing filters for use with TLV320AIC32, 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
TLV320AIC32 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 TLV320AIC32, enable the Effect Filters by checking
the boxes again.
6.10.3
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 12
, 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.
SBAU113 – November 2005
TLV320AIC32EVM and TLV320AIC32EVM-PDK User's Guide
21
