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OPA656: Transimpedance Amplifier for Analytical Instrumetns

Arivalagan Arivu
Prodigy 150 points

Part Number: OPA656
Other Parts Discussed in Thread: TINA-TI

Hello all,

I'm in the process of designing a transimpedance amplifier for an analytical instrument. The requirement is such that the process generates a very low current which is multiplied by microchannel plate. Even after this, the current is between 1 to 5 pA and the bandwidth requirement is around 300 MHz. The transient response requirement is also very high.

I've designed a transimpedance amplifier with OPA656 which is a 500MHz unity gain-bandwidth product opamp. I've installed a 1Gohm feedback resistor..I'm about to sweep this resistor value in order to find the correct resistor value to faithfully amplify the current signal.

For testing purposes, I use an old photodiode..whose specifications I don't know clearly.

 

My questions are:

what are the systematic steps I should follow to design the amplifier?

2. I don't have ready-made access to sophisticated measuring instruments like keysight/Tektronics DSO and the like.

Having said that suppose I want to characterize the frequency response and transient response of the amplifier.

But, function generators can only generate voltage sources...or how do I generate current sources in order to measure the frequency response of the TIA.....or whether the facility of generating current sources is available with the function generator?

3.I've got the same question for measuring the transient response of the TIA

 

to put in other words: How do I measure the frequency response of the transimpedance amplifier? and How do I generate such a small current in order to measure the frequency response and the transient response..

 

Kindly provide necessary support in this regard.

 

Regards,

M Arivalagan

Research Scholar

Anna University

Chennai

Tamilnadu

Ph.:+91 75023 98999

email: arivalagan13@gmail.com

  • 0
    TI__Genius 16735 points

    Hello,

    The first step you can do is build your proposed design in TINA-TI. You can then simulate your frequency and transient responses. You can confirm operation as well as well confirm stability of your design. TINA very closely models the behavior of the amplifiers.

    You can download the TINA model reference design for the part you need under the tools and software section of the product folder.
    There are also many precision labs videos you can google that help guide you on how to measure stability and frequency response in TINA.

    Thanks!

    -Karan