CS4328 Datasheet, PDF (10/31 Pages) Cirrus Logic – 18-Bit, Stereo D/A Converter for Digital Audio

CS4328
Performance Plots
The following collection of CS4328 measure-
ment plots (IWR = 48 kHz) were taken with an
Audio Precision Dual Domain System One. All
FFT plots are 16,384 point.
Figure 9 shows the frequency response with a
48 kHz input word rate. The response is very flat
out to half the input word rate.
Figure 10 shows the muted noise with all zeros
data into the CS4328. This plot is dominated by
the noise floor of the System One.
Figure 11 shows the unmuted noise. This data
was taken by feeding the CS4328 continuous ze-
ros, but pulling CALI low. This unmutes the
output stage of the CS4328. This plot shows the
noise shaping characteristics of the delta-sigma
modulator combined with the analog filter.
Figure 12 shows the A-weighted THD+N vs sig-
nal amplitude for a dithered 1kHz input signal.
Notice that there is no increase in distortion as
the signal level decreases. This indicates very
good low-level linearity, one of the key benefits
of the delta-sigma technique.
Figure 13 shows the fade-to-noise linearity test
result using track 20 of the CBS CD-1. The in-
put test signal is a dithered 500 Hz sine wave
which gradually fades from -60 dB level to -120
dB. During the fading, the output level from the
CS4328 is measured and compared to the ideal
level. Notice the very close tracking of the out-
put level to the ideal, even at low level inputs of
-90 dB. The gradual shift of the plot away from
zero at signal levels < -100 dB is caused by the
background noise starting to dominate the meas-
urement.
Figure 14 shows the impulse response, taken
from the single positive full scale value on track
17 of the CD-1 test disk. Notice the high degree
of symmetry, indicating good phase linearity.
10
Figure 15 shows a 16K FFT plot result, with a
1 kHz -90 dB dithered input. Notice the com-
plete lack of distortion components and tones.
Figure 16 shows a bandlimited, 10 Hz to
22 kHz, time domain plot of the CS4328 output
with a 1 kHz, -90 dB dithered input. Notice the
clear residual sine wave shape, in the presence of
noise.
Figure 17 shows the monotonicity test result
plot. The input data to the CS4328 is +1 LSB, -1
LSB four times, then +2 LSB, -2 LSB four times
and so on, until +10 LSB, -10 LSB. This data
pattern is taken from track 21 of the CD-1 test
disk. Notice the increasing staircase envelope,
with no decreasing elements. Notice also the
clear resolution of the LSB. For this test, one
LSB is a 16-bit LSB.
The following tests were done by filtering the
analog output of the CS4328 with the System
One analyzer 1 kHz notch filter to reduce the
peak signal level. The resulting signal was then
amplified and applied to the DSP module, avoid-
ing distortion in the System One A/D converter.
Figure 18 shows a 16K FFT Plot with a 1 kHz,
0 dB input. Notice the low order harmonic dis-
tortion at < -100 dB.
Figure 19 shows a 16K FFT Plot with a 1 kHz,
-10 dB input. Notice the almost complete ab-
sence of distortion, with a small residual 2nd
harmonic at -110 dB.
DS62F3