0.35µm 16-BIT 44.1KHZ SIGMA-DELTA STEREO DAC
BW0405XA
FUNCTIONAL DESCRIPTION
MCLK
DEEM
DN
MDATA
MLD
MUTEL
Compensation Filter
&
Sinc Filter
&
SDATA
BCK
S/P Converter
&
4bit DAC
&
AoutL
AoutR
Anti-Image
Filter
De-emphasis/
FIR Filter
Σ∆
64Fs
1bit
LRCK
Attenuator
4Fs/8Fs
16bits
SC-Postfilter
1Fs/2Fs
16bits
Modulator
Figure 4. Funtional Block Diagram
Fig4 is the 1bit 4th order sigma-delta DAC block daigram. S/P Converter converts serial 16bit input data to parallel
16bit data. Digital input data is attenuated by MICOM interface pin control. Compensation Filter compensates gain
droop in Passband by Sinc Filter and Sigma-Dellta Modulator Signal Transfer Function. De-emphasis Block de-
emphasizes pre-emphasised input data to emphssize high frequency in audible band. FIR Filter perfroms 4X
interpolation. And it outputs 4Fs(DN='Low') rate data or 8Fs(DN='High') rate data by variabled input data rate. It
also removes the images of the input signal that are present at multiples of the input sample frequency. And Sinc
filter makes the constant 64Fs rate data by 16 times or 8 times upsampling FIR Filter output data according to
DN(Double/Normal Mode) Pin Selection. This operation intorduces a sinc function responce on the resulting
frequency spectrum, which greatly attenuates the energy of images at the multifules of 4Fs(or 8Fs).
Digital sigma-delta modulator of bit-stream type has the IFL (Inverse-Follower-Leader) topology, and it performs a
noise-shaping function. The modulator shapes the quantization noise by suppressing its in-band component and
pushes the noise energy of outside the band-of-interest without deteriorating the audio input signal. The 64 times
oversampled 1-bit PDM outputs from the modulator drives a analog postfilter.
The analog postfilter comprises SC-postfilter, anti-imaging filter. The SC-postfilter removes the quantization noise
shaped to out-of-band by digital sigma-delta modulator. This analog filter has the good clock jitter characteristc and
very linear characteristic. And following the CTF(continuous time filter) removes the sampling images and makes
the high resolution analog output.
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SAMSUNG [ SAMSUNG ]
