CXA2647N
• Focus Error
The signals input to the A and C pins and the B and D pins are arithmetically amplified and the focus error
signal is output.
This circuit has ROM/RW switching and offset addition functions.
VC
100k
ROM
23.5k
A6
30k
C8
30k
B7
30k
D9
ROM
VOFST
RW
30k
47k
200k
FE = Gain { (B + D) – (A + C) }
Low frequency gain ROM: 15.5dB
RW: 27.5dB
RW
100k
ROM
47k
RW
200k
FEI 17
124
50k
DVC
16 FE
124
Cut-off frequency fc (typ.) ROM: 400kHz
RW: 300kHz
• Tracking Error
The signals input to the E and F pins are arithmetically amplified and the tracking error signal is output.
This circuit has ROM/RW switching and offset addition functions.
VC
Control bias
VC – 1V to VC + 1V
TE_BAL 19
20k
F
11
gm
ROM
VOFST
VC
RW
20k
63k
251k
10k
63k ROM
251k RW
20k 10 E gm
VC
20k
10k
31.5k
125.5k
ROM RW
TE = Gain (F – E)
Low frequency gain ROM: 16dB
RW: 28dB
18 TE
TE balance adjustment
(F – E) low frequency gain = ±6dB
Cut-off frequency fc (typ.)
ROM: 200kHz
RW: 150kHz
VC
External resistance value vs. Low frequency gain for E and F input pins
22
15.5
12.5
10k
20k
30k
Resistance value [Ω]
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