CS4330 Datasheet, PDF (7/38 Pages) Cirrus Logic – 8 Pin Stereo D/A Converter for Digital Audio

CS4330, CS4331, CS4333
GENERAL DESCRIPTION
The CS4330, CS4331, and CS4333 are complete
stereo digital-to-analog systems including digital
interpolation, 128× third-order delta-sigma digi-
tal-to-analog conversion, digital de-emphasis and
analog filtering, Figure 2. This architecture pro-
vides a high tolerance to clock jitter.
The primary purpose of using delta-sigma modu-
lation techniques is to avoid the limitations of
laser trimmed resistive digital-to-analog con-
verter architectures by using an inherently linear
1-bit digital-to-analog converter. The advantages
of a 1-bit digital-to-analog converter include:
ideal differential linearity, no distortion mecha-
nisms due to resistor matching errors and no
linearity drift over time and temperature due to
variations in resistor values.
Digital Interpolation Filter
The digital interpolation filter increases the sam-
ple rate by a factor of 32 and is followed by a 4×
digital sample-and-hold to effectively achieve a
128× interpolation filter. This filter eliminates
images of the baseband audio signal which exist
at multiples of the input sample rate, Fs. This
allows for the selection of a less complex analog
filter based on out-of-band noise attenuation re-
quirements rather than anti-image filtering.
Following the interpolation filter, the resulting
frequency spectrum has images of the input sig-
nal at multiples of 128× the input sample rate.
These images are removed by the external ana-
log filter.
Delta-Sigma Modulator
The interpolation filter is followed by a third-
order delta-sigma modulator which converts the
22-bit interpolation filter output into 1-bit data at
128× .
Switched-Capacitor Filter
The delta-sigma modulator is followed by a
digital-to-analog converter which translates the
1-bit data into a series of charge packets. The
magnitude of the charge in each packet is deter-
mined by sampling of a voltage reference onto a
switched capacitor, where the polarity of each
packet is controlled by the 1-bit signal. This
technique greatly reduces the sensitivity to clock
jitter and is a major improvement over earlier
generations of 1-bit digital-to-analog converters.
Digital
Input
Interpolator
Delta-Sigma
Modulator
DAC
Figure 2. System Block Diagram
Analog
Low-Pass
Filter
Analog
Output
DS136F1
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