Complete 12-Bit/10-Bit 6 MSPS
CCD/CIS Signal Processors
a
AD9807/AD9805
FEATURES
FUNCTIO NAL BLO CK D IAGRAM
Pin Com patible 12-Bit and 10-Bit Versions
12-Bit/ 10-Bit 6 MSPS A/ D Converter
Integrated Triple Correlated Double Sam pler
3-Channel, 2 MSPS Color Mode
1؋
– 4؋
Analog Program m able Gain Am plifier
Pixel-Rate Digital Gain Adjustm ent
Pixel-Rate Digital Offset Adjustm ent
Internal Voltage Reference
PIXEL PIXEL
OFFSET GAIN
VREF
AD9807/AD9805
GAIN
REGISTERS
RED
8-10
12-10
VINR
VING
VINB
PGA
PGA
PGA
CDS
CDS
CDS
REF
ADC
GREEN
BLUE
12-10
–
MUX
DOUT
X
No Missing Codes Guaranteed
Microprocessor-Com patible Control Interface
+3.3 V/ +5 V Digital I/ O Com patibility
Low Pow er CMOS: 500 m W
CSB
RD
WR
A2
ODD
EVEN
INPUT
OFFSET
MPU
MPU
PORT
PORT
64-Pin PQFP Surface Mount Package
CONFIG
REGS
A1
A0
CDSCLK1 CDSCLK2
ADCCLK
P RO D UCTIO N D ESCRIP TIO N
On-Chip CDS—An integrated 3-channel correlated double
The AD9807 and AD9805 are complete CCD/CIS imaging
decoders and signal processors on a single monolithic integrated
circuit. T he input of the AD9807/AD9805 allows direct ac
coupling of the charge-coupled device (CCD) or contact image
sensor (CIS) output(s). T he AD9807/AD9805 includes all the
circuitry to perform three-channel correlated double sampling
(CDS) and programmable gain adjustment of the CCD output;
a 12-bit or 10-bit analog-to-digital converter (ADC) quantizes
the analog signal. After digitization, the on-board digital signal
processor (DSP) circuitry allows pixel rate offset and gain correc-
tion. The DSP also corrects odd/even CCD register imbalance
errors. A parallel control bus provides a simple interface to
8-bit microcontrollers. T he AD9807/AD9805 comes in a
space saving 64-pin plastic quad flatpack (PQFP) and is specified
over the commercial (0°C to +70°C) temperature range. By
disabling the CDS, the AD9807/AD9805 are also suitable for
non-CCD applications, or applications that do not require
CDS, such as CIS signal processing.
sampler allows easy ac coupling directly from the CCD sensor
outputs. Additionally, the CDS reduces low frequency noise
and reset feedthrough.
On-Chip Voltage Reference—T he AD9807/AD9805 includes a
2 V bandgap reference that allows the input range of the device to
be configured for input spans up to 4 V.
6 MSPS A/D Converter—A highly linear 12-bit or 10-bit A/D
converter sequentially digitizes the red, green and blue CDS
outputs ensuring no missing code performance. The user may also
configure the AD9807/AD9805 for single channel operation.
Digital Gain & Offset Correction—Pixel rate digital gain and
offset correction blocks allow precise repeatable correction of
imaging system error sources.
Digital I/O Compatibility—The AD9807/AD9805 offers
+3.3 V/+5 V logic level compatibility.
Pin-Compatible 12-Bit and 10-Bit Versions—T he AD9807 is
also offered in a pin-compatible 10-bit version, the AD9805,
allowing upgrade-ability and simplifying design issues across
different scanner models.
P RO D UCT H IGH LIGH TS
T he AD9807/AD9805 offers a complete, single chip CCD
imaging front end in a 64-pin plastic quad flatpack (PQFP).
On-Chip PGA—T he AD9807/AD9805 includes a 3-channel
analog programmable gain amplifier; it is programmable from
1× to 4× in 16 increments.
REV. 0
Inform ation furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assum ed by Analog Devices for its
use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norw ood, MA 02062-9106, U.S.A.
Tel: 617/ 329-4700
Fax: 617/ 326-8703
World Wide Web Site: http:/ / w w w .analog.com
© Analog Devices, Inc., 1997