cxa2555q Sony Electronics, cxa2555q Datasheet - Page 15

• Manufacturer Part Number: cxa2555q
• Description: Rf Amplifier For Cd Player/cd-rom
• Manufacturer: Sony Electronics

RF DC Amplifier
The signal currents from the photodiodes A, B, C and D are I-V converted and input to Pins 3 and 4 as PD1 =
A + C, PD2 = B + D.
These signals are added by the RF summing amplifier, inverted by the RF drive amplifier and output to Pin 32.
The VCA control voltage on Pin 28 is used for the gain adjustment.
The low frequency component of the RFO output voltage is as follows:
Focus Error Amplifier
The operation of PD2-PD1 is performed and the resulting signal is output to Pin 15.
The low frequency component of the FE output voltage is as follows:
V
V
FE
RFO
=
= 10.9
= 4.9
174k
16k
(PD2 – PD1)
(PD1 + PD2)
(PD2 – PD1)
I-V
I-V
PD1
PD2
(RFC voltage = 1/2 VC)
I-V
I-V
3
4
PD1
PD2
20k
20k
3
4
16k
16k
Vc
164k
– 15 –
10k
14
47k
27p
RF
Summing Amp
FE B
SUM OUT
174k
27p
Vc
30
Focus
Error Amp
87k
Vc
VCA
47k
28
RF C
15
RFO
FE
32
CXA2555Q