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Please Suggest a very high speed TIA for my requirement

Other Parts Discussed in Thread: OPA857, LMH6629

i have a photo diode on which a laser of 10ns pulse width and nearly 2ns rise time falls

i have to digitalize the 10ns pulse and measure its pulse width and confirm its pulse width 

my application is very critical and oriented on measuring the pulse width

i have current limits from 10nA to 100mA (limits can be altered or flexible), may be i have to go for current limiters

first i thought of going for a non AGC approach where i identified that i am always making the opamp saturated and further not able to maintain the pulse width and not able to reach the dynamic range also

is it possible for me to use the bare die packages like ONET2591TA ??? i did not see even a EVM or kindly suggest me an AGC based TIA where i can achieve a good dynamic range of atleast 40-50dB, but when i see these datasheets its evident that the current noise itself is 200+ nA and maximum current they can bear is 2mA and dont know whether have any protection diodes,

i tired to post it in optical fiber comm forum, but did not get any reply, this is more relevant to this forum i feel

  • Hello Daram,

    I will forward your request to our transimpedance amplifier (TIA) expert. Our LMH6629 is a very fast amplifier that works well as a TIA, we also have the OPA857 which is a dedicated TIA.  There may be better options as well.



  • Daram,

    As Loren suggested the LMH6629 and OPA857 are the fastest amplifiers in our portfolio. To achieve the dynamic range you are hoping for you will have to either do a discrete log amp or discrete AGC with clamping.

  • i dont know why TI stopped those TIA opamps with AGC which were available as die , more over these opamps ckts you have suggested i need many such which will make my design bulky, i am tarketing a airborne application, for which size of board is constraint, none of the opamps you mentioned are available as die form from  TI, i need them in die because i can make a hybrid in a TO package itself, 

    now this problem will make to put the hundreds of opamps (almost 250) :( 

    thanks for the info

  • Hello Daram,

    I will forward your request for die packaged amplifiers to our sales group.