NE5210 データシートの表示（PDF） - Philips Electronics
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NE5210 Datasheet PDF : 14 Pages
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Philips Semiconductors
Transimpedance amplifier (280MHz)
Product specification
NE5210
R1
IC1
INPUT
IB
IIN
Q1
VIN
IF
VCC
R3
Q2
R2
Q3
VEQ3
RF
R4
Figure 3. Shunt-Series Input Stage
SD00329
The operating point of Q1, Figure 2, has been optimized for the
lowest current noise without introducing a second dominant pole in
the pass-band. All poles associated with subsequent stages have
been kept at sufficiently high enough frequencies to yield an overall
single pole response. Although wider bandwidths have been
achieved by using a cascode input stage configuration, the present
solution has the advantage of a very uniform, highly desensitized
frequency response because the Miller effect dominates over the
external photodiode and stray capacitances. For example, assuming
a source capacitance of 1pF, input stage voltage gain of 70, RIN =
60Ω then the total input capacitance, CIN = (1+7.5) pF which will
lead to 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
3.5pA/√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 RMS noise current is strongly determined by the
quiescent current of Q1, the feedback resistor RF, and the
bandwidth; however, it is not dependent upon the internal
Miller-capacitance. The measured wideband noise was 66nARMS 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, DE, in a 200MHz bandwidth assuming
IINMAX = 240µA and a wideband noise of IEQ=66nARMS for an
external source capacitance of CS = 1pF.
(Max. input current) (PK)
DE + 20log (Peak noise current) (RMS) @ Ǹ 2
+
20
log
(240 @
(Ǹ 2 66
10*6)
10*9)
+ 68dB
In order to calculate the optical dynamic range the incident optical
power must be considered.
For a given wavelength λ; (meters)
Energy of one Photon = hc watt sec (Joule)
l
Where h=Planck’s Constant = 6.6 × 10-34 Joule sec.
c = speed of light = 3 × 108 m/sec
c / λ = optical frequency (Hz)
No. of incident photons/sec= where P=optical incident power
P
No. of incident photons/sec = hs
l
where P = optical incident power
P
No. of generated electrons/sec = h
@
hs
l
where η = quantum efficiency
+
no.
of
generated electron hole
no. of incident photons
paris
P
N
I +h
@
hs
l
@
e
Amps
(Coulombsń
sec.)
where e = electron charge = 1.6 × 10-19 Coulombs
h @e
Responsivity R = hs Amp/watt
l
I + P@R
Assuming a data rate of 400 Mbaud (Bandwidth, B=200MHz), the
noise parameter Z may be calculated as:1
Z
+
IEQ
qB
+
66 @ 10*9
(1.6 @ 10*19)(200 @ 106)
+ 2063
where Z is the ratio of RMS noise output to the peak response to a
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 10-9 BER is:
PavMIN +
12
hc
l
B
Z
+
12
2.3 @ 10*19
200 @ 106 2063
+ 1139nW + * 29.4dBm
where h is Planck’s Constant, c is the speed of light, λ is the
wavelength. The minimum input current to the NE5210, at this input
power is:
IavMIN
+
qPavMIN
l
hc
+
1139 @ 10*9 @ 1.6 @ 10*19
2.3 @ 10*19
= 792nA
Choosing the maximum peak overload current of IavMAX=240µA, the
maximum mean optical power is:
PavMAX
+
hcIavMAX
lq
+
2.3
1.6
@
@
10*19
10*19
240
@
10*6
Thus the optical dynamic range, DO is:
DO = PavMAX - PavMIN = -4.6 -(-29.4) = 24.8dB.
1995 Apr 26
12
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