This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

OPA857: low-noise alternative

Part Number: OPA857
Other Parts Discussed in Thread: LMH32404, LMH32401, OPA818, OPA859

Hello, team.

Could you please suggest, do we have any updates of OPA857 device?

Customer is wondering if we can propose any modern alternative with better noise specs for using with HPDA avalanche photodiode in frequency range of DC...100MHz?

Thank you.

  • Hello Slava, 

      We do have a lot of updated devices within that bandwidth. However, would like to optimize the selection through a few more questions

      Can the customer share:

    1. APD (avalanche photodiode) capacitance (input cap to the amplifier)
    2. Input current range
    3. Output voltage range (gain needed)

    Thank you,


  • Hi Sima,

    1. APD (avalanche photodiode) capacitance (input cap to the amplifier): 0.4..0.5 pF
    2. Input current range: 0.1...100 nA
    3. Current amplification: 10 000...20 000 
  • Hello Slava,

      Thank you for gathering this information. If the are looking to keep the differential output. I would recommend the LMH32401 which also has an integrated current limiting clamp, 2k and 20kohm gain switch, and ambient light cancellation. It has around the same noise at the same bandwidth and gain configuration. The LMH32401 is also available in a quad channel version, LMH32404.

      For discrete solutions (not integrated TIA), the customer would need to target an amplifier with a GBW of at least 650MHz and above. But, the customer might have to increase the amplification. It is hard to narrow down a device that has both low current and voltage noise. Here are a list of amplifiers that could work. In this list, customer should look at OPA859 and OPA818.

    Thank you,