DC photocurrent:
a few mA => A transimpedance of 1k Ohm will realize the output of ~a few V.
A few mA of DC current produces the shot noise photocurrent of 20~30pA/rtHz
RF photocurrent:
Resonant circuit resistance @25MHz: 100~300 Ohm.
Reduced to 100 by the shunt resistance of 150 Ohm
MAX4107 required minimum gain of 10 for the stability
-> Total Transimp. R=1K
-> Andrew said R=1K gives 13dBm output (1.4Vpk @25MHz)
-> This corresponds to 200 V/us of slewrate. This is ~40% of the full scale. (Too big)
input referred current noise ~ 12pA/rtHz ==> Shot noise intercept current ~0.44mA
If we reduce the shunt resistance to get the total transimpedance of 500Ohm
=> Beat output: 7dBm (0.7Vpk@25MHz, ~20% of the full slewrate)
input referred current noise ~24pA/rtHz ==> Shot noise intervept current ~ 1.8mA
Questions:
- Can we torelate this noise level (24pA/rtHz)?
- Or do we have MAX4106 (min gain 5), or something else for a replacement?
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