Models 2051 & 2053
General Features & Principles • 11
where
P
is the input optical power in Watts,
R
is the
photodetector’s response factor in V/mW, and
G
is the
amplifier’s gain setting.
Estimate the value of the response factor by dividing the
responsivity shown in Figure 1 by 1.5.
For example, the Model 2051 on the 1x10
3
gain setting
and with 10 µW of optical power at 900 nm on the
photodiode will have an output voltage of
approximately
(0.01 mW)·(0.35 V/mW)·(1x10
3
) = 3.5 V
.
The maximum differential optical power that can be
detected by the photoreceiver is determined by the
input optical power at which either stage of the
transimpedance gain saturates. We can calculate the
saturation power at 900 nm for the Model 2051 at its
maximum output voltage of
±
7 V with fresh batteries
or operating from an external ±15 VDC power supply.
Using the expression 7 V =
P
sat
·R·G
, the Model 2051 has
a differential saturation power of 20 mW for the lowest
gain setting up to 0.7 µW for the highest gain setting.
At other wavelengths where the responsivity is lower,
the saturation power increases inversely with response
factor.
Note:
Note:
205x 10MHz Adj Rcvr revA.fm Page 11 Monday, January 10, 2005 9:29 AM
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