AD9891 Datasheet, PDF (31/58 Pages) Analog Devices – CCD Signal Processors with Precision Timing™ Generator

example, the Mosaic Separate Steering Mode accommodates the
popular “Bayer” arrangement of Red, Green, and Blue filters
(see Figure 38a).
The same Bayer pattern can also be interlaced, and the Mosaic
Interlaced Mode should be used with this type of CCD (see
Figure 38b). The color steering performs the proper multiplex-
ing of the R, G, and B gain values (loaded into the PxGA gain
registers) and is synchronized by the vertical (VD) and horizon-
tal (HD) sync pulses. The PxGA gain for each of the four
channels is variable from –2 dB to +10 dB, controlled in 64
steps through the serial interface. The PxGA gain curve is
shown in Figure 40.
VD
HD
SHP/SHD
6
COLOR
STEERING
CONTROL
2
4:1
MUX
3
PxGA
CONTROL
STEERING
REGISTER
MODE
BITS D0:D2
SELECTION
GAIN0
GAIN1
GAIN2
GAIN3
PxGA GAIN
REGISTERS
CDS
PxGA
VGA
Figure 37. PxGA Block Diagram
FLD
ODD FIELD
AD9891/AD9895
CCD: PROGRESSIVE BAYER
R Gr R Gr LINE0
MOSAIC SEPARATE COLOR
STEERING MODE
GAIN0, GAIN1, GAIN0, GAIN1, ...
Gb B Gb B LINE1
R Gr R Gr LINE2
GAIN2, GAIN3, GAIN2, GAIN3, ...
GAIN0, GAIN1, GAIN0, GAIN1, ...
Gb B Gb B
Figure 38a. CCD Color Filter Example: Progressive Scan
CCD: INTERLACED BAYER
EVEN FIELD
R Gr R Gr LINE0
R Gr R Gr LINE1
R Gr R Gr LINE2
R Gr R Gr
MOSAIC INTERLACED
COLOR STEERING MODE
GAIN0, GAIN1, GAIN0, GAIN1, ...
GAIN0, GAIN1, GAIN0, GAIN1, ...
GAIN0, GAIN1, GAIN0, GAIN1, ...
ODD FIELD
Gb B Gb B LINE0
Gb B Gb B LINE1
Gb B Gb B LINE2
Gb B Gb B
GAIN2, GAIN3, GAIN2, GAIN3, ...
GAIN2, GAIN3, GAIN2, GAIN3, ...
GAIN2, GAIN3, GAIN2, GAIN3, ...
Figure 38b. CCD Color Filter Example: Interlaced
EVEN FIELD
VD
HD
PxGA GAIN
REGISTER
X
X
0
1
0
1
2
3
2
3
0
1
0
1
010123230101
0
NOTES
1. VD FALLING EDGE WILL RESET THE PxGA GAIN REGISTER STEERING TO “0101” LINE.
2. HD FALLING EDGES WILL ALTERNATE THE PxGA GAIN REGISTER STEERING BETWEEN “0101” AND “2323” LINES.
3. FLD STATUS IS IGNORED.
Figure 39a. Mosaic Separate Color Steering Mode
FLD
ODD FIELD
EVEN FIELD
VD
HD
PxGA GAIN
REGISTER
XX
0
1
0
1
0
1
0
1
0
1
0
1
232323232323
0
NOTES
1. FLD FALLING EDGE (START OF ODD FIELD) WILL RESET THE PxGA GAIN REGISTER STEERING TO “0101” LINE.
2. FLD RISING EDGE (START OF EVEN FIELD) WILL RESET THE PxGA GAIN REGISTER STEERING TO “2323” LINE.
3. HD FALLING EDGES WILL RESET THE PxGA GAIN REGISTER STEERING TO EITHER “0” (FLD = ODD) OR “2” (FLD = EVEN).
Figure 39b. Mosaic Interlaced Color Steering Mode
REV. A
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