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OPA392: OPA392

Sumeet Patil
Prodigy 220 points
Part Number: OPA392

Tool/software:

Hello TI,

I am looking for an opamp with with following parameters:

1) Auto zeroing

2) Input bias current: 1-1000 fA

3) input offset voltage: 5nV-500 nV

4) input offset drift: 1 - 5 nV/DegC

5) noise: 1) F @ 1 Hz 1nV/sqrtHz

Please suggest me a suitable opamp, I intend to use it as charge amplifier.

  • 0
    TI__Mastermind 23598 points

    Patil,

    1. We do not have an auto-zero (zero-drift) amplifier with these specifications.
    2. The term zero-drift refers to both  auto zero and chopper amplifiers.  Both types of devices correct offset and offset drift.  TI has not developed a true auto-zero since the mid-2000's, as copper amplifiers offer many advantages. 
    3. This article covers background and non-idealities of choppers: https://www.ti.com/lit/wp/sboa586/sboa586.pdf 
    4. Zero-drift amplifiers have a transient current on their inputs that makes if difficult to achieve femto-amp bias current levels.  Normally, the room temperature IB is in the 100pA level.  Across temperature this will double every 10C.
    5. Achieving less than 1uV of offset is challenging.  See table 1.1 in the attached document to see the range of offset on available devices.
    6. Achieving 1nV/sqrtHz is challenging for a zero-drift device.  Our best in class non-chopper (traditional bipolar) is 1.1nV/rtHz.

    Sorry that I can't help.  I am not sure how you can achieve this set of specifications.  We do not have anything in this range.

    Best regards, Art