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CXA2525AM/AN

Tracking Error Amplifier

Each signal current from the photodiodes E and F is I-V converted and input to Pins 8 and 9. These signals

undergo operational amplification at the tracking error amplifier and tracking drive amplifier, and are output to

Pin 12.

The low frequency component of TE output voltage is as follows:

×

× (F – E)

= 11.1

× (F – E)

Center Voltage Generation Circuit

The maximum current is approximately ±3mA.

APC Circuit

When the laser diode is driven with constant current, the optical output possesses large negative temperature

characteristics. Therefore, the current must be controlled with the monitor photodiode to ensure the output

E

F

I-V

44k

320k

5P

TE

73.4k

VC

VC

112k

I-V

44k

112k

8

9

12

11P

112k

44k

320k

73.4k

VR

25

VC

40k

40k

Vc Buffer

Vcc

Vcc

10

PD

10k

55k

56k

10k

22

100

500

100µ

10µH

1µ

LD

1k

56k

10k

1

2

1.25V