LG GDR-8161B Service Manual page 14

3-3. TRACKING ERROR (TE)
3-3-1. TE for DVD-ROM (DPD)
A
H.P.F
57
D
H.P.F.
58
C
59 H.P.F
B
H.P.F.
60
TE signal for DVD-ROM is made by DPD (Differential Phase Detect) method.
TE signal is made that add voltage obtain form phase differnece of front spot A, D to voltage obtain two phase
difference of rear spot B, C.
Final stage amp gain is determined by register "TEG" and TE signal amplitude is about 1.65Vpp. (Center
voltage of TE signal is about 1.65V)
Balance of TE signal center voltage (1.65V) is decided by current which feed into IC101 6 pin from IC201 58pin
during initialization.
Adjustment is operated by monitoring TE signal balance which feed into IC201 111pin.
22
EQ
DPD
EQ
EQ
DPD
EQ
Tracking error Circuit
DPP
TESEL
TBAL
Offset
6
Add circuit
TEG
TE
18
1.65V
1.65V
1.65Vpp
Center Voltage = 1.65V
IC201
3.3V
PWM
58
Balance
Detect
A/D
111