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Entry  Thu Feb 7 19:24:57 2013, Riju, Update, , Photodiode transimpedance reflshotnoise.pdf
    Reply  Fri Feb 8 17:15:56 2013, Jenne, Update, RF System, MC REFL Photodiode transimpedance 
       Reply  Fri Feb 8 20:27:56 2013, Koji, Update, RF System, MC REFL Photodiode transimpedance 
Message ID: 8027     Entry time: Thu Feb 7 19:24:57 2013     Reply to this: 8038
Author: Riju 
Type: Update 
Subject: Photodiode transimpedance 

 Summary: Measurement and plot of shot-noise-intercept-current for MC REFL PD. 

Motivation:It is to measure the shot noise intercept current for MC REFL PD.


Result: The final plot is attached here. The plot suggests that the value of shot-noise-intercept current is 1.9mA



The plot is for the measured data of Noise voltage (V/sqrt(Hz)) vs DCcurrent(A). The fitted plot to this measured data follows the noise equation

Vnoise = gdet* sqrt[ 2e (iDC+idet)] ,  where gdet= transimpedance of the PD in RF region ~600

To get an approximate idea of the shot noise intercept current, we may follow the same procedure described in 7946 

In the present case minimum noise value is 1.46e-08 V/sqrt(Hz)

Therefore dark current(in2) ~dark noise voltage/RF transimpedance ~25pA/sqrt(Hz)

Therefore the approximate shot noise intercept current value is (25/18)^2 ~ 1.92mA, which matches well to the fitted value.



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