CS4327 Datasheet, PDF (13/36 Pages) Cirrus Logic – Low Cost, 20-Bit, Stereo, Audio D/A Converter

CS4327
Analog Output and Filtering
The CS4327 contains an on-chip buffer amplifier
producing single-ended outputs. Each output will
produce a nominal 2.83 Vpp (1 Vrms) output with
a 2.3 volt common mode for a full scale digital in-
put.
The CS4327 filter is a linear phase design and does
not include phase or amplitude compensation for
an external filter. Therefore, the DAC system phase
and amplitude response will be dependent on the
external analog circuitry. The second-order low-
pass filter with a -3 dB frequency of 50 kHz shown
in Figure 10 will give good results in most applica-
tions. The design of this filter is discussed in AN55,
the Crystal Applications Note "Design Notes for a
2-pole Filter." Figure 11 displays the the output
spectrum of the CS4327. Figure 12 displays the
output spectrum following the 2-pole filter. Notice
the attenuation beyond 50 kHz.
20k
150 pF
10k
3.4k
_
+
100 pF
Figure 10. 2-pole Butterworth Fillter
Figure 11. CS4327 Output Spectrum
Fs = 48 kHz
DS190F1
Figure 12. 2-pole Filtered Output Spectrum
Fs = 48 kHz
13