CXA2542AQ
Description of Functions
RF Amplifier
The photodiode currents input to the input pins (PD1 and PD2) are each I-V converted through a 58kΩ
equivalent resistor by the PD I-V amplifiers. These signals are added by the RF summing amplifier, and the
photodiode (A + B + C + D) current-voltage converted voltage is output to the RFO pin. An eye-pattern check
can be performed at this pin.
1k
30k
3.3µ
RF_O
RF_M
32
31
A
C
58k
PD1
10k
10k
VA
V1
36
37
iPD1→
FOK
DEFECT
PD1 IV AMP
58k
B
D
RF SUMMING AMP
V3
VC
VC
PD2
iPD2→
VB
V2
PD2 IV AMP
The low frequency component of the RFO output voltage is
30k
VRFO = –
(VA + VB – 2V3) + V3
10k
= –3 {–58kΩ (iPD1 + iPD2) + V1 + V2 – 2V3} + V3, and
the setting is V1 = V2 = V3, then
VRFO = 174kΩ × (iPD1 + iPD2) + V3
– 16 –
SONY [ SONY CORPORATION ]
