– 11 –

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

RW

100k

23.5k

30k

ROM

A

DVC

VOFST

6

FEI 17

FE

16

30k

C 8

30k

B

30k

47k

200k

47k

50k

100k

200k

7

D

ROM

RW

ROM

RW

9

124

124

FE = Gain { (B + D) – (A + C) }

Low frequency gain

ROM: 15.5dB

RW: 27.5dB

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.

ROM

RW

11

18

VC

VC

F

VC

VOFST

ROM

Control bias

VC – 1V to VC + 1V

RW

VC

E

TE

TE_BAL

10

gm

gm

19

20k

20k

10k

10k

31.5k

125.5k

63k

251k

63k

ROM

RW

251k

20k

20k

TE = Gain (F – E)

Low frequency gain

ROM: 16dB

RW:

28dB

TE balance adjustment

(F – E) low frequency gain = ±6dB

Cut-off frequency fc (typ.)

ROM: 200kHz

RW:

150kHz

External resistance value vs. Low frequency gain for E and F input pins

Resistance value [

Ω]

10k

22

15.5

12.5

20k

30k