guidance on the circuit analysis

Low Noise Single Supply Photodiode Amplifier

I am trying to understand the circuit shown above, with one JFET transistor at left side acting a current buffer and right hand side with a op amp.

this is a low noise transimpedance circuit,  which I think I can use or modified this circuit and used in my design, sensitive to noise and a current signal needed to be amplified to voltage signal in the end. 

the problem is that I am not quit sure how to analyse the circuit, should I use small-signal analysis? Do I need to derive the transfer function? 

why the Bandwidth is 2MHZ and where is the cut off frequency? and is the system stable or not? 

Can someone give me a clue or answer, please? 

Thanks

Parents
  • Due to an operator error (mine) my original reply was accidentally deleted. I will try and reconstruct it:

    The circuit came from a respected manufacturer's archive of application notes, and the pulse response shows no ringing--therefore it looks stable. The bandwidth is determined by R1 and the parasitic 0.08pF capacitance.  1/2piRC ~ 2MHz. However, depending on a 0.08pF parasitic capacitor could be problematic.

    There are many tradeoffs in designing a low noise, high gain, high bandwidth photodiode preamp, and you might want to check out some of our literature on the subject:

    Sensor Signal Conditioning, Chapter 7

    MT-035, MT-050, MT-059

    We also have several photodiode amplifier reference designs complete with documentation that are available for a nominal cost:

    CN0272, CN0312, CN0363

    And also a design tool specifically for photodiode preamps:  Photodiode Wizard

    Let us know if you have any further questions.

    Walt

Reply
  • Due to an operator error (mine) my original reply was accidentally deleted. I will try and reconstruct it:

    The circuit came from a respected manufacturer's archive of application notes, and the pulse response shows no ringing--therefore it looks stable. The bandwidth is determined by R1 and the parasitic 0.08pF capacitance.  1/2piRC ~ 2MHz. However, depending on a 0.08pF parasitic capacitor could be problematic.

    There are many tradeoffs in designing a low noise, high gain, high bandwidth photodiode preamp, and you might want to check out some of our literature on the subject:

    Sensor Signal Conditioning, Chapter 7

    MT-035, MT-050, MT-059

    We also have several photodiode amplifier reference designs complete with documentation that are available for a nominal cost:

    CN0272, CN0312, CN0363

    And also a design tool specifically for photodiode preamps:  Photodiode Wizard

    Let us know if you have any further questions.

    Walt

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