SA5212AFE PHILIPS [NXP Semiconductors], SA5212AFE Datasheet - Page 12

• Manufacturer Part Number: SA5212AFE
• Description: Transimpedance amplifier 140MHz
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
DYNAMIC RANGE
The electrical dynamic range can be defined as the ratio of
maximum input current to the peak noise current:
Electrical dynamic range, D
I
external source capacitance of C
In order to calculate the optical dynamic range the incident optical
power must be considered.
For a given wavelength ;
Energy of one Photon = hc
Where h=Planck’s Constant = 6.6
c = speed of light = 3
c /
1998 Oct 07
INMAX
D
D
Transimpedance amplifier (140MHz)
E
E
(dB) + 20 log
(dB) + 20 log
= optical frequency
D
= 120 A and a wideband noise of I
E
I
+
IN
V
(Peak noise current)
IN
(Max. input current)
Figure 12. Shunt-Series Input Stage
INPUT
(120 @ 10
(120mA)
(73nA)
( 2 52nA)
10
I
F
l
8
I
B
E
m/sec
watt sec (Joule)
, in a 200MHz bandwidth assuming
PHOTODIODE
*6
+ 64dB
R1
)
S
Q1
= 1pF.
10
R
F
-34
I
C1
EQ
Joule sec.
INPUT
=52nA
Q2
R2
GND
RMS
Figure 11. Transimpedance Amplifier
Q
Q3
1
R
SD00329
1
R3
V
R4
1
R
EQ3
5
for an
Q
V
2
R
CC
2
Q
3
R
R
3
4
Q
4
+
R
V
7
12
CC1
Q
15
R
R
No. of incident photons/sec= where P=optical incident power
No. of incident photons/sec =
where P = optical incident power
No. of generated electrons/sec = h @
where
where e = electron charge = 1.6
Responsivity R =
Assuming a data rate of 400 Mbaud (Bandwidth, B=200MHz), the
noise parameter Z may be calculated as:
Z +
where Z is the ratio of
single hole-electron pair. Assuming 100% photodetector quantum
efficiency, half mark/half space digital transmission, 850nm
lightwave and using Gaussian approximation, the minimum required
optical power to achieve 10
where h is Planck’s Constant, c is the speed of light,
wavelength. The minimum input current to the SA5212A, at this
input power is:
12
I + P @ R
14
+
NI + h @
200 @ 10
P
I
qB
I
EQ
no. of generated electron hole paris
avMIN
avMIN
GND
+ 897 @ 10
= quantum efficiency
+
R
15
= 624nA
Q
2
(1.6 @ 10
+ 12 hc
+ qP
VB2
16
no. of incident photons
6
hc
P
l
1625 + 897nW + * 30.5dBm,
R
13
@ e Amps (Coulombs sec.)
h@e
avMIN
l
2.3 @ 10
52 @ 10
hc
+
l
*19
*9
B Z + 12 (2.3 @ 10
Q
Amp/watt
RMS
11
hc
@ 1.6 @ 10
)(200 @ 10
l
Q
*9
*19
noise output to the peak response to a
-9
12
BER is:
SD00328
hc
P
l
V
OUT–
OUT+
CC2
*19
10
6
)
+ 1625
-19
hc
P
l
Coulombs
1
*19
)
Amp
Amp
Product specification
SA5212A
is the