CXA1782 SONY [Sony Corporation], CXA1782 Datasheet - Page 14

• Manufacturer Part Number: CXA1782
• Description: RF Signal Processing Servo Amplifier for CD players
• Manufacturer: SONY [Sony Corporation]

Description of Functions
RF Amplifier
The photo diode currents input to the input pins (PD1 and PD2) are each I-V converted via a 58kΩ equivalent
resistor by the PD I-V amplifiers. these signals are added by the RF summing amplifier, and the photo diode
(A + B + C + D) current-voltage converted voltage is output to the RFO pin. An eye-pattern check can be
performed at this pin.
The low frequency component of the RFO output voltage is V
Focus Error Amplifier
The focus error amplifier calculates the difference between output VA and VB of the RF I-V amplifier, and
output current-voltage converted voltage of the photo diode (A + C – B – D).
The FEO output voltage (low frequency) is V
Be aware that the rotation of the focus bias volume has reversed for the usual CD RF IC.
1k
3.3µ
C
D
A
B
– (B + D)
– (A + C)
iPD1
iPD2
PD1
PD2
VB
VA
35
36
VC
VC
32k
32k
PD1 IV AMP
PD2 IV AMP
FEO
25p
VC
58k
58k
V
= 5.4
EE
87k
– 14 –
37
47k
VA
VB
(V
164k
A
– V
10k
10k
RFO
174k
25p
FE_BIAS
V
B
FE AMP
CC
) = (iPD2 – iPD1)
= 2.2
32
VC
(V
RF_M
1 FEO
A
RF SUMMING AMP
+ V
22k
B
) = 127.6kΩ
315kΩ.
31
RF_O
(iPD1 + iPD2).
CXA1782CQ/CR