Samsung Electronics
5-1
5. Special Circuit Descriptions
5-1 RF Amp Block
5-1-1 RF Amplifier
5-1-2 Focus Error Amp
PD1
PD2
VC
RF-
RFO
RF SUMMINGAMP
VC
VC
VB
10K
58K
IV AMP
VA
10K
58K
IV AMP
+
-
+
-
+
-
65
66
73
74
32K
160K
4K
32K
164K
3K
+
-
+
-
+
-
63
59
FE1
VB>
VA>
SW1
FEBIAS
FEBIAS
sev-stopb
VC
fe-stopb
fcmpo
sev-stop
X1
X2
X4
X8
X16
<5 Bit Counter>
The two currents from input pins PD1 (A+C) and PD2 (B+D) are converted into voltages through I/V Amp,
and they are added to RF summing Amp. The photo diode (A+B+C+D) signal which is I-V changed is
outputted by RFO (pin74). At this pin, the eye pattern can be checked.
The output of the focus error amp is the difference between RF I-V AMP(1) output Va and RF I-V AMP(2)
output Vb,just is the Photo Diode ((A+C) - (B+D)) signal which is I-V changed.
The focus error bias voltage applied to the (+) of focus error amp can be changed by D/A converter as shown in
diagram, so that the offset of focus error amp can be adjust automatical.
Focus error bias can be adjusted from the range of +100mV ~ -100mV by connectiong the resistor with pin 63
(FEBIAS).
Содержание MAX-870
Страница 2: ...ELECTRONICS Samsung Electronics Co Ltd Jan 1998 Printed in Korea Code no AH68 20177A ...
Страница 8: ...Remote Control ...
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