Dynamic range calculations, Sa5211, Philips semiconductors – Philips SA5211 User Manual
Page 15
Philips Semiconductors
SA5211
Transimpedance amplifier (180 MHz)
Product specification
Rev. 03 — 07 October 1998
15 of 28
9397 750 07427
© Philips Electronics N.V. 2001. All rights reserved.
strongly determined by the quiescent current of Q
1
, the feedback resistor R
F
, and the
bandwidth; however, it is not dependent upon the internal Miller-capacitance. The
measured wideband noise was 41 nA RMS in a 200 MHz bandwidth.
14. 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
E
, in a 200 MHz bandwidth assuming I
INMAX
= 60
µ
A and
a wideband noise of I
EQ
= 41 nA
RMS
for an external source capacitance of C
S
= 1 pF.
(5)
(6)
(7)
In order to calculate the optical dynamic range the incident optical power must be
considered.
For a given wavelength
λ
;
Energy of one Photon =
watt sec (Joule)
Where h = Planck’s Constant = 6.6
×
10
-34
Joule sec.
c = speed of light = 3
×
10
8
m/sec
c /
λ
= optical frequency
No. of incident photons/sec =
where P = optical incident power
No. of generated electrons/sec =
where
η
= quantum efficiency
D
E
(Max. input current)
(Peak noise current)
------------------------------------------------
=
D
E
(dB)
20 log
60
10
6
–
×
(
)
2 41 10
9
–
(
)
-----------------------------
=
D
E
dB
(
)
20 log
60
µ
A
(
)
58
nA
(
)
--------------------
60db
=
=
hc
λ
------
P
hc
------
λ
------
η
P
hc
------
λ
------
×
no. of generated electron hole pairs
no. of incident photons
------------------------------------------------------------------------------------
=