SA5211D PHILIPS [NXP Semiconductors], SA5211D Datasheet - Page 14

• Manufacturer Part Number: SA5211D
• Description: Transimpedance amplifier 180MHz
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
60 then the total input capacitance, C
only a 12% bandwidth reduction.
NOISE
Most of the currently installed fiber-optic systems use non-coherent
transmission and detect incident optical power. Therefore, receiver
noise performance becomes very important. The input stage
achieves a low input referred noise current (spectral density) of
2.9pA/ Hz. The transresistance configuration assures that the
external high value bias resistors often required for photodiode
biasing will not contribute to the total noise system noise. The
equivalent input
quiescent current of Q
bandwidth; however, it is not dependent upon the internal
Miller-capacitance. The measured wideband noise was 41nA RMS
in a 200MHz bandwidth.
DYNAMIC RANGE CALCULATIONS
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 /
No. of incident photons/sec=
No. of generated electrons/sec = h @
where
where e = electron charge = 1.6
Responsivity R =
1998 Oct 07
I + P @ R
INMAX
D
D
E
E
Transimpedance amplifier (180MHz)
+
NI + h @
(dB) + 20 log
(dB) + 20 log
= optical frequency
D
no. of generated electron hole paris
= 60 A and a wideband noise of I
E
= quantum efficiency
+
(Peak noise current)
no. of incident photons
(Max. input current)
hs
P
l
RMS
@ e Amps (Coulombs sec.)
h@e
( 2 41 10
(60mA)
(58nA)
hs
l
(60 @ 10
noise current is strongly determined by the
Amp/watt
1
, the feedback resistor R
10
l
8
+ 60dB
E
m/sec
*6
watt sec (Joule)
, in a 200MHz bandwidth assuming
*9
hs
)
P
l
)
S
where P=optical incident power
10
= 1pF.
10
-19
hs
P
l
-34
IN
Coulombs
EQ
= 4 pF which will lead to
Joule sec.
=41nA
F
, and the
RMS
for an
14
Assuming a data rate of 400 Mbaud (Bandwidth, B=200MHz), the
noise parameter Z may be calculated as:
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 SA5211, at this input
power is:
Choosing the maximum peak overload current of I
maximum mean optical power is:
Thus the optical dynamic range, D
D
This represents the maximum limit attainable with the SA5211
operating at 200MHz bandwidth, with a half mark/half space digital
transmission at 850nm wavelength.
I
Z +
1. S.D. Personick, Optical Fiber Transmission Systems ,
Plenum Press, NY, 1981, Chapter 3.
avMIN
P
D
O
200 @ 10
avMAX
O
= P
P
INPUT
+ 20.8dB
+ P
avMIN
I
qB
avMAX
+ qP
EQ
+ 86mW or * 10.6dBm (optical)
+
+ 1139nW + * 29.4dBm
avMAX
6
= 500nA
+
+ 12 hc
+ 707 @ 10
(1281) + 719nW + * 31.5dBm
hcI
avMIN
- P
A1
(1.6 @ 10
Figure 11. SA5211 – Block Diagram
avMAX
lq
avMIN
R
* P
F
l
hc
l
B Z + 12 @ 2.3 @ 10
avMIN
41 @ 10
2.3 @ 10
+ 2.3 @ 10
RMS
= -4.6 -(-29.4) = 24.8dB.
*19
*9
Joule
1.6 @ 10
1
noise output to the peak response to a
@ 1.6 @ 10
)(200 @ 10
-9
+ * 31.5 * (* 10.6)
*9
BER is:
*19
@ Joule
A2
sec @ q + I
*19
*19
O
is:
*19
6
)
60 @ 10mA
1
+ 1281
*19
Product specification
A3
A4
avMAX
SA5211
is the
=60 A, the
OUTPUT –
OUTPUT +
SD00327