XRD98L59 Datasheet, PDF (23/37 Pages) Exar Corporation – CCD Image Digitizers with CDS, PGA and 10-Bit A/D

XRD98L59
BLACK LEVEL OFFSET CALIBRATION
CCD
Signal
CDS
+
2/)
+
2/)
10-bit ADC
Reg
10
DB[9:0]
From Serial
Interface
Registers
4-bit CDAC
10-bit FDAC
ManDAC
CDAC, FDAC
Coarse
Accumulator
Fine
Accumulator
Black Level
Offset Calibration
Loop
Offset Calibration Logic
CalHold, SpeedUp
Gain Code
DNS
Target Offset Code
DNS
Filter
+
+
-
Pixel
Averager
10
Hot Pixel
Clipper
Figure 15. Black Level Offset Calibration Block Diagram
To get the maximum color resolution and dynamic range,
the XRD98L59 uses a digitally controlled feedback cir-
cuit to correct for offset in the CCD signal as well as offset
in the CDS, PGA & ADC signal path. This calibration is
done while the CCD outputs Optical Black (OB) pixels.
The CAL input signal is used to define when the CCD
output contains OB pixels. The calibration logic will take
into account the internal pipeline delay.
Rev. 2.00
23