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CXA1372BQ/BS

Mirror Circuit

The mirror circuit performs peak and bottom hold after the RFI signal has been amplified.

For the peak hold, a time constant can follow a 30kHz traverse, and, for the bottom hold, one can follow the

rotation cycle envelope fluctuation.

Through differential amplification of the peak and bottom hold signals H and I, mirror output can be obtained by

comparing an envelope signal J (demodulated to DC) to signal K for Which peak holding at a level 2/3 that of

the maximum was performed with a large time constant. In other words, mirror output is low for tracks on the

disc and high for the area between tracks (the MIRR areas). In addition, a high signal is output when a defect

is detected. The mirror hold time constant must be sufficiently large in comparison with the traverse signal.

20k

0.033µ

RFO

RFI

CP

MIRROR

COMPARATOR

PEAK &

BOTTOM

HOLD

× 2.2

K

MIRROR HOLD AMP

J

H

I

× 1

G

MIRROR AMP

MIRR

DGND

29

38

39

RFO

H

L

0V

0V

0V

0V

G

(RFI)

H

(PEAK HOLD)

I

(BOTTOM HOLD)

(MIRROR HOLD)

J

K

MIRR