22
1.65V
1.65V
Balance
Detect
PWM
58
111
IC201
DPD
DPD
EQ
EQ
EQ
EQ
H.P.F
H.P.F.
H.P.F
H.P.F.
TESEL
DPP
TEG
18
Offset
Add circuit
3.3V
6
TE
TBAL
1.65Vpp
Center Voltage = 1.65V
A/D
57
58
59
60
A
D
C
B
3-3. TRACKING ERROR (TE)
3-3-1. TE for DVD-ROM (DPD)
Tracking error Circuit
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.