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Hi,
I want to measure the potential (voltage) difference and current between two dissimilar metals (in a electrolyte) for datalogging. I was wondering if it is possible to use a DAC (sinking), to measure the current directly (instead using a shunt)? and maybe use a ADC for the voltage...
HI
Okay, I am confused. Can you guys elaborate that with an example or proper literature?
By the way, what is the gain? Usually in a tranimpedance amplifer you have A/V gain. Is the gain here decided by R1 and R2.
And How do you do a proper simulation – that simulates the current pulses...
Hi.
I am designing a Bandpass transimpedance amplifier. But I unfortunately I have trouble understanding some basic stuf. The circuit I am planning to use is shown below. It is a reversed biased photodiodes.
I know that the lower and upper frequencies in a active bandpassfilter is found by...
Ah okay. So it basically puts a requirement to my open-loop gain.
I have calculated my resistor to be 12Mohm ( Voutmax (5V)-Vmin(0.1V)/Inmax (400nA)).
(2) Then I calculate the Feedback capacitor fc=1/(2pi*Cf*Rf) at 60kHz, which gives 221fF. (to obtain stability)
(3) Then I calculate fz...
The transimpedance doesn’t present a small impedance, because a Gain error signal Vo/AOL remains across the diode and its capacitances, which gives us the time constant: RfCD/(AoL).. See attached picture.
Okay, Super. With the settling time vs duty-cycle. I found this eq. Cd is the output capacitance of the photodiode, epilson is the settling accuracy, A is the open-loop gain. D is the duty-cycle.
Have anybody seen these equations before, why does the settling time depend on the open loop gain...
Hmm. I am not quite sure, I am understanding you. My 3db cutoff (bandwidth) should be at least 60 KHz (fp) Right?
Using the eq. fp = 1/(2pi*CF*RF). Which parameters should I tweak on. I know Cf creates a pole that counteracts the zero from beta, but how should I chose Rf...
Okay thank you.
I am using TIA for a current to voltage conversion. The photocurrent is 600nA, the question is therefore should I use an input (in series with the photodiode) resistor to get Vin (how big should this resistor be)– since the gain is A = Vout/Vin?
The input signal is modulated...
Okay, thank u.
Sorry – for not be being precise, I meant the shot-noise (from the photodiode) generated by the ambient light ��.
I have been trying to calculate the shot-noise current. I found out that room lighting is approximately 500 lux – which corresponds to 3-5 Watts/m^2...
Hi
I am trying to estimate the shot-noise from ambient light sources (sunlight and Fluorescent lamps).
I expect to shield my photodiode as good as possible - so no direct light is hitting it.
Second, what is the relationship between photodiode area size and noise from ambient light - is it...
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