CX-3164
6
1
2
4
1
2
3
4
C
D
F
A
B
E
11
E
VREF
11
112k
112k
63k
45.36k
63k
160k
160k
45.36k
161k
80k
160k
60k
20k
130
129
TEOFF setup
TE A/D
Inside TEC
Pickup Unit
P5
P10
E
F
UPD63763CGJ
CD CORE UNIT
+
-
+
-
+
-
+
-
+
-
+
-
-
+
VREF
TEO
TE-
TEC
TE2
139
138
140
141
47p
10000p
1.1.3 Focus error amplifier
The photo-detector outputs (A + C) and (B + D) are passed through the differential amplifier and the error amplifier, and (A
+ C - B - D) is provided from the pin 136 as the FE signal. The low frequency component of the voltage FE is calculated
as below.
FE = (A + C - B - D) x 8.8k / 10k x 111k / 61k x 160k / 72k
= (A + C - B - D) x 3.5
For the FE outputs, an S-shaped curve of 1.5 Vp-p is obtained with the REFO as the reference. The cutoff frequency for
the subsequent stage amplifiers is 14.6 kHz.
1.1.4 RFOK circuit
This circuit generates the RFOK signal, which indicates the timing to close the focus loop and focus-close status during
the play mode, from the pin 55. As for the signal, "H" is output in closing the focus loop and during the play mode.
Additionally, the RFOK becomes "H" even in a non-pit area, since the DC level of the RFO signal is peak-held in the
subsequent digital block and compared at a certain threshold level to generate the RFOK signal. Therefore, the focus is
closed even on a mirror-surface area of a disc. This signal is also supplied to the microcomputer via the low-pass filer as
the FOK signal, which is used for protection and gain switching of the RF amplifier.
1.1.5 Tracking error amplifier
The photo-detector outputs E and F are passed through the differential amplifier and the error amplifier to obtain (E - F),
and then provided from the pin 139 as the TE signal. The low frequency component of the voltage TE is calculated as
below.
TEO = (E - F) x 63k / 112k x 160k / 160k x 181k / 45.4k x 160k / 80k
= (E - F) x 4.48
For the TE output, TE waveform of about 1.3 Vp-p with the REFO as the reference. The cutoff frequency in the
subsequent is 21.1 kHz.
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