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Optical Pickup
Chipset with Photodetector ICs Supports High-Speed
Writing to CD and DVD
CXA2702GA/CXA2716GA/CXA2701GA
Although it has only been
a year since Sony released the CXA2676GA and
CXA2677GA* for DVD x8-speed recording, DVD recording
speed has already reached x16. Sony's newly-developed
CXA2701GA and CXA2702GA/CXA2716GA optical pickup
photodetector ICs (PDICs) support this x16 record
speed.
*: See CX-News, Volume 32, for details on the
CXA2676GA and CXA2677GA. |
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CXA2702GA/CXA2716GA |
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RF/Servo PDICs
* Supports high-speed CD/DVD write operations
(CD-R: x52-speed, DVD-R: x16-speed)
*WPP1 (B+C) and WPP2 (A+D) outputs, which are
optimal for DVD address pit detection
* Variable limiter function
* CXA2702GA: Eight-division photodiode CXA2716GA:
Twelve-division photodiode
* 18-pin LGA COB small package |
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CXA2701GA |
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Laser Front Monitor PDIC
* Differential output
* Two-channel structure (Vin1, Vin2)
* 12-pin LGA COB small package |
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CXA2702GA/CXA2716GA |
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The CXA2702GA is a
photodetector IC (PDIC) that was developed as
the photo-detector for optical pickups used
in DVD±R/RW recording drives. Like the
earlier x8-speed CXA2677GA, it provides the
WPP1 and WPP2 signals that are optimal for address
pit signal detection. In increasing the recording
speed to x16, Sony added a 3x gain switching
function to WPP1 and WPP2. The new IC thus has
an additional 2 bits of control compared to
the earlier gain switching system. The CXA2702GA
also now provides an input pin that can control
the output limiter voltage externally so that
applications can set the limiter voltage to
provide optimal pickup performance. Note that
although the CXA2702GA includes a built-in 8-division
photodiode that supports the same differential
push-pull method as the earlier product (CXA2677GA),
Sony has also added to the product lineup the
CXA2716GA, which includes a built-in 12-division
photodiode that supports the differential astigmatism
method. Both the CXA2702GA and CXA2716GA feature
the extremely fast main output settling time
(for a 1 V amplitude) of 6 ns. |
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CXA2701GA |
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Like the earlier x8-speed
CXA2676GA, the CXA2701GA adopts a two-channel
structure to allow the CD laser and the DVD
laser power levels to be set individually. However,
the output was changed to the differential type
in this new product. This was because the output
at the read power became even smaller due to
lowering the gain of the first stage I-V amplifier
(transimpedance amplifier) to 1/√2 to
support x16-speed laser diodes. Switching to
a differential amplifier improves the signal-to-noise
ratio by √2 and also allows the common
mode noise in the transmission system to be
cancelled. |
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Support for
Lead-Free Mounting |
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Since the chip on
board (COB) package adopted for these ICs has
excellent resistance to heat, these ICs support
mounting with lead-free solder. They allow two-pass
reflow mounting with a peak temperature of 250°C.
Note: Since the thermal resistance is strongly
influenced by the usage environment, verify
the details of the specifications in advance,
or contact your Sony representative for consultation.
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•••• Mr.TESHIMA and Mr.SHIDOOKA
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Our achievement of
x16-speed DVD recording required pushing our
circuit technologies to the limit to get the
utmost performance from Sony's process technologies.
The two of us on this development team had to
come up with a lot of mutual support and encouragement
during this design effort. We are probably not
the only ones who are hoping that this achievement
marks the end of the competition for ever higher
speeds. |
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See all articles
with figures and tables.  |
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Vol.36 |
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