Lge Internal Use Only - LG -S367 Service Manual

3.12.2 Digital Part
The digital part of the X-GOLD™213 audio front-end comprises an interface to the TEAKLite® bus, interfaces to
the interrupt units of TEAKLite®, digital interpolation filters for oversampling digital-to-analog conversion,
digital decimation filters for analog-to-digital conversion and an interface to the analog part of the audio
front-end. For the digital microphone all the filtering is done in a dedicated hardware. The output sample
stream is then fed in a duplicated ring buffer structure like the data from the analog microphone path (after
A/D conversion and subsequent digital filtering).
Interpolation Filter
The interpolation path of the X-GOLD™213 audio front-end increases the sampling rate of the audio samples
to the rate of the digital-to-analog converter. Because the input sampling rates can vary between 8 kHz and
47.619 kHz the filter characteristic and oversampling ratio can be adjusted to the respective sampling rate.
The requirements for the interpolation filters depend on the sampling rate, because a sufficient out-of-band
discrimination in the audio frequency band (20 Hz,...,20 kHz) has to be ensured.
Decimation Filter
The digital decimation filter on X-GOLD™213 has two operating modes: 8 kHz output sampling rate and 16
kHz output sampling rate (or 16 kHz output sample rate and 16kHz bandwidth in case of doubled ASMD
clock).

LGE Internal Use Only

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3. TECHNICAL BRIEF
Only for training and service purposes