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Audio Signal Processing LSI
Provides Professional Audio Quality from Miniature Speakers
CXD3772GG
Sony has now developed the CXD3772GG audio signal processor
LSI. This device is based on professional audio technologies and
includes A/D converter, D/A converter, and PLL circuits on chip.
This LSI allows dedicated programs to be downloaded and parameters
to be adjusted and provides audio fidelity improvement effects
comparable to the functions in professional audio equipment.
The CXD3772GG makes it possible to achieve significant improvements
in audio quality in accordance with the physical characteristics
of the equipment. For example it can improve the insufficient
bass response in equipment that uses miniature speakers,
such as cellular phones, portable audio equipment, and miniature
headphones. |
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CXD3772GG |
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* Miniature dedicated audio processor:
Bass enhancement,
Stereo spatial enhancement function,
Dynamic range control,
Equalization, and other functions.
* Stereo signal processing
* Built-in A/D and D/A converters, PLL, and
digital interface
* Power saving standby mode
* Miniature 44-pin VFBGA package |
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Miniature Dedicated Audio
Processor |
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Sony developed the CXD3772GG as a
new dedicated audio product. It provides
the following functions for audio quality
adjustment that are used in professional
audio.
• Bass enhancement (low band enhancement
effect that is based on the characteristics
of human hearing and operates
without increasing the low-band gain)
• Stereo spatial enhancement function
• Dynamic range control
• Equalization (correction of the frequency
characteristics to match the
speaker system)
These functions are implemented in a programmable
manner. (Note, however, that
program development and audio quality
tuning require an experienced specialist.)
Programs and adjustment parameter values
are loaded over an I2C bus (that supports
fast mode).
Parameter values are changed dynamically. |
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Stereo Signal Processing |
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The CXD3772GG provides two 1-bit ΔΣ
A/D converters and two D/A converters
on chip. After the input analog signals are
converted to digital, they are processed by
the internal processor and then converted
back to analog signals for output.
Since the CXD3772GG also includes a
digital audio interface, it supports the following
signal conversions.
• Analog input → digital output
• Digital input → analog output
The CXD3772GG generates an internal
1024fs clock from an externally input
clock using a built-in PLL circuit. It support
fs = 44.1 kHz. |
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Power Saving Standby Mode |
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Since the RAM and core power supplies
are separate, it is possible to leave only
the power supply for the RAM, which
holds downloaded programs and parameters,
operating and shut off all other
power supply systems.
At the same time as reducing power consumption
in standby mode, this makes it
possible to return to normal operation
without having to re-download the program.
Also, since the CXD3772GG includes an
analog bypass signal path, power can be
reduced even further by using that signal
path when signal processing is not required. |
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Audio Characteristics |
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• Total harmonic distortion + noise: 70 dB
or better
• Signal-to-noise ratio: 82 dB or better
• Channel separation: 80 dB or better |
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IC Specifications |
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• Supply voltages:
Digital and PLL system supply
voltage: 1.8 V, A/D and D/A converters:
2.85 V (3.3 V max.)
• Operating temperature: -30 to +85°C
• Package: 44-pin VFBGA (0.5 mm pitch)
• Package dimensions: 4.0 mm × 4.0 mm |
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•••• Section 6 Product Department 7 System LSI Business Division Semiconductor Business Group ••••
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Although the CXD3772GG is not
an extremely large-scale LSI, it
was still difficult to create an
evaluation environment, since it
is a mixed-signal analog/digital
device. Nevertheless, the development
team worked together as a
unit to see the device through to
mass production. I think you will
find that including this LSI in your
products will provide a previously
unknown level of audio quality
improvement in portable equipment. |
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See
all articles with figures and tables.  |
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Vol.48 |
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