Rainbow Electronics TH7841A - Manual (Page 7)

7
TH7841A
1998A–IMAGE–05/02
Figure 3. CTF Typical Curves (2854 K Source)
Electro-optical
Performance Without
Infrared Cut-off
Filtering
The TH7841A special semiconductor process exploits the silicon’s high near infrared
sensitivity while maintaining good imaging performance in terms of response uniformity
and resolution. Typical changes in performance with and without IR filtering are summa-
rized below.
Complementary
Operating Modes
The TH7841A may be used in several configurations in regards to video output sam-
pling and charge sensing reset.
1. Sampling options
Inhibition of internal sampling pulses allows two possibilities:
a. no sampling: video output delivered in unsampled form,
b. sampling by external clocks: external sampling pulses directly applied to
Φ
ECHA
,
Φ
ECHB
inputs.
If internal sampling clocks S Φ
ECHA
and S Φ
ECHB
are not used, it is recommended to
unpower the corresponding clock drivers, as this will greatly reduce on-chip power
consumption.
2. External reset position
The position and period of the charge reset clocks may be optimized by using external
clocks on
Φ
RA
and
Φ
RB
inputs. This is especially interesting to optimize the video outputs
for Correlated Double Sampling (in order to reduce noise and improve S/N Ratio).
Control signals to be applied in the different configurations are shown in Table 6.
With IR Cut-off Filter No IR Cut-off Filter
Average Video Signal Due To a Given Scene Illumination V
OS
V
OS
x 4
PRNU (Single Defects Excluded) ±5% ±5%
CTF at Nyquist Frequency 70% 50%