ODHKGA4143-02
Electronic Components
KGA4143
BLOCK DIAGRAM AND APPLICATION OUTLINES
Vd
0.1µF
220pF
V(PD)
Photo
KG A4143
Diode
IN
O UTN
Outp ut Offset
Ad justment Circuit
15pF
20koh m
20koh m
Vd1
Vd2
O UTP
Blocking
Capacitor
15 kohm
20pF
OP Am p.
-
+
15pF
G ND1 Cap
Pmon
Vth2
Vth1
G ND2
220pF
10~40ohm
0.1µF
GND1, GND2:
Ground.
Vd1, Vd2:
Power supply.
IN:
Input; Connect to photo detector anode.
OUTP:
Positive output.
OUTN:
Negative output.
Cap:
Pad for external capacitor to ground; The low frequency cutoff is reduced by
adding external capacitors. KGA4143 has on-chip 15k resistors with shunt
20pF capacitors to ground. With 100nF external capacitors, the low frequency
cutoff will be about 30kHz. To prevent the peaking at low-cutoff frequency, a
few ten ohm damping resistor, next to the largest external capacitor (between
“Cap”
pad and the external capacitor or between the capacitor and ground), is
required.
Vth1, Vth2:
Output offset adjustment (These
pads can be left floating. For the
best performance, it is recommended to use either.);
[If use this function]
One of these pads (user can select either, but the methods how to use are
different. See the controllability of Vth1 and Vth2, in previous page.) enables
the user to modify the bias offset of differential outputs, to optimize the BER
performance, especially, under low optical signal-to-noise ratio (OSNR)
conditions. The typical value is about +0.6V. No bypass capacitor is required
for these pads. The input resistances of Vth1 and Vth2 are about 520.
Pmon:
Power monitor (This
pad can be left floating.);
[If use this function]
This
pad provides a voltage proportional to optical input power (1V/mW). Without
input signal, the voltage is approximately (Vd-1.8)V. If it is used, more than
50k load is required.
9
OKI [ OKI ELECTRONIC COMPONETS ]
