NE5210 Philips, NE5210 Datasheet - Page 13

• Manufacturer Part Number: NE5210
• Description: Transimpedance amplifier 280MHz
• Manufacturer: Philips

Philips Semiconductors
This represents the maximum limit attainable with the NE5210
operating at 200MHz bandwidth, with a half mark/half space digital
transmission at 850nm wavelength.
APPLICATION INFORMATION
Package parasitics, particularly ground lead inductances and
parasitic capacitances, can significantly degrade the frequency
response. Since the NE5210 has differential outputs which can feed
back signals to the input by parasitic package or board layout
capacitances, both peaking and attenuating type frequency
response shaping is possible. Constructing the board layout so that
Ground 1 and Ground 2 have very low impedance paths has
produced the best results. This was accomplished by adding a
ground-plane stripe underneath the device connecting Ground 1,
Pins 8–11, and Ground 2, Pins 1 and 2 on opposite ends of the
SO14 package. This ground-plane stripe also provides isolation
between the output return currents flowing to either V
2 and the input photodiode currents to flowing to Ground 1. Without
this ground-plane stripe and with large lead inductances on the
board, the part may be unstable and oscillate near 800MHz. The
easiest way to realize that the part is not functioning normally is to
measure the DC voltages at the outputs. If they are not close to their
1995 Apr 26
Transimpedance amplifier (280MHz)
10 H
NOTE:
The NE5210/NE5217 combination can operate at data rates in excess of 100Mb/s NRZ
The capacitor C7 decreases the NE5210 bandwidth to improve overall S/N ratio in the DC–50MHz band, but does create extra high frequency noise
on the NE5210 V
L3
10 H
L2
10 F
C10
C12
10 F
220
R2
CC
.01 F
pin(s).
C9
R3
47k
C11
.01 F
C13
100pF
LED
V
D1
OUT
(TTL)
10
1
2
3
4
5
6
7
8
9
THRESH
LED
C
GND
FLAG
JAM
V
V
GND
TTL
PKDET
CCD
CCA
OUT
A
D
Figure 4. A 50Mb/s Fiber Optic Receiver
R
R
PKDET
OUT
OUT
CC2
C
C
HYST
IN
IN
IN
IN
AZP
AZN
C1
C2
1B
1A
1B
8B
1A
8A
or Ground
+V
18
16
CC
20
19
17
15
14
13
12
11
C7
47 F
.01 F
0.1 F
C8
100pF
13
quiescent values of 3.3V (for a 5V supply), then the circuit may be
oscillating. Input pin layout necessitates that the photodiode be
physically very close to the input and Ground 1. Connecting Pins 3
and 5 to Ground 1 will tend to shield the input but it will also tend to
increase the capacitance on the input and slightly reduce the
bandwidth.
As with any high-frequency device, some precautions must be
observed in order to enjoy reliable performance. The first of these is
the use of a well-regulated power supply. The supply must be
capable of providing varying amounts of current without significantly
changing the voltage level. Proper supply bypassing requires that a
good quality 0.1 F high-frequency capacitor be inserted between
V
pins as possible. Also, the parallel combination of 0.1 F capacitors
with 10 F tantalum capacitors from each supply, V
the ground plane should provide adequate decoupling. Some
applications may require an RF choke in series with the power
supply line. Separate analog and digital ground leads must be
maintained and printed circuit board ground plane should be
employed whenever possible.
Figure 4 depicts a 50Mb/s TTL fiber-optic receiver using the BPF31,
850nm LED, the NE5210 and the NE5214 post amplifier.
GND
CC1
R4
4k
and V
10
11
12
13
14
8
9
GND
GND
GND
GND
OUT
GND
OUT
CC2
, preferably a chip capacitor, as close to the package
GND
GND
V
V
CC
CC
NC
I
NC
IN
1
7
6
5
4
3
2
.01 F
C4
10 H
L1
Product specification
CC1
NE5210
10 F
R1
100
C3
and V
OPTICAL
BPF31
INPUT
SD00330
CC2
1.0 F
.01 F
C5
C6
, to