cxa1982q Sony Electronics, cxa1982q Datasheet - Page 19

• Manufacturer Part Number: cxa1982q
• Description: Rf Signal Processing Servo Amplifier For Cd Players
• Manufacturer: Sony Electronics

Focus OK Circuit
The focus OK circuit creates the timing window okaying the focus servo from the focus search state.
The HPF output is obtained at Pin 30 from Pin 31 (RF signal), and the LPF output (opposite phase) of the
focus OK amplifier output is also obtained.
The focus OK output reverses when V
Note that, C5 determines the time constant of the HPF for the mirror circuit and the LPF of the focus OK
amplifier. Ordinarily, with a C5 equal to 0.01µF selected, the fc is equal to 1kHz, and block error rate
degradation brought about by RF envelope defects caused by scratched discs can be prevented.
DEFECT Circuit
After inversion, RF O signal is bottom held by means of the long and short time constants. The long time-
constant bottom hold keeps the mirror level prior to the defect.
The short time-constant bottom hold responds to a disc mirror defect in excess of 0.1msec, and this is
differentiated and level-shifted through the AC coupling circuit.
The long and short time-constant signals are compared to generate at mirror defect detection signal.
0.01µ
RF_O
C5
31
RF_O
RF_I
RF
a
b
e
c
a
30
31
RFO
DEFECT
AMP
BOTTOM
HOLD (1)
solid line
CC1
DEFECT
DEFECT AMP
2
FOK
RF
FOCUS OK AMP
b
DEFECT
CB
RFI
15k
– V
28
0.01µ
1
RFO
VG
DEFECT BOTTOM
–0.37V.
– 19 –
54k
HOLD
0.625V
CC1
92k
27
0.033µ
FOCUS OK
COMPARATOR
DEFECT COMPARATOR
26
CC2
d
c
DEFECT SW
e
H
L
20k
d
V
CC
BOTTOM
HOLD (2)
dotted line
CC2
24
25
SENS
FOK
CXA1982Q