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OPA140: IBias vs Temperature

Don Schelle
Expert 4150 points
Part Number: OPA140
Other Parts Discussed in Thread: OPA2140, OPA145

Hello,

I'm looking for Ibias across temperature data for the OPA140.   Typical is good, but min/max would be ideal.    Do we have this information?

Don

  • 0
    TI__Genius 15060 points
    Hi Donald,
    Ib for OPA140 is specified to be ±3nA max from -40°C to 125°C, with a max spec at room temperature of ±10pA. This leakage is predominantly diode leakage, and will be worse at higher temperatures, better at lower temperatures.
  • 0 in reply to Alex Davis
    TI__Expert 4150 points
    Thanks Alex,

    I appreciate the timely response. Perhaps my question was a little too vague. Specifically, I'd like to know the following:

    1. Do we have a graph that shows Ib vs Temperature for the OPA140 or perhaps the OPA2140 (dual version)?
    a. If so, does that graph show min/max curves? Or only typical?
    2. Does a 10oC rise in temperature roughly correspond to a doubling of Ib?
    3. Are the ESD structures largely responsible for Ib?
    a. Do package parasitics matter with respect to the OPA140? I suspect no given the higher (relatively speaking) Ib in the pA/nA.
    4. How is Ib affected with respect to the common mode voltage?
    5. Are there any good app-notes on the subject?

    Many thanks in advance.

    Don
  • 0 in reply to Don Schelle
    TI__Genius 15060 points
    Hi Donald,
    1. I'm not aware of a graph of Ib vs temperature that's publicly available. OPA145 is built on the same process as OPA140, and should exhibit the same trend in Ib over temperature. Its bias current is a little higher, but we do publish an Ib vs temperature curve in that datasheet.
    a. That graph does not show min/max curves, however, as the curves section in the datasheet represents typical specifications (unless otherwise noted).
    2. The 10°C doubling rule-of-thumb should hold.
    3. For FET and CMOS input amplifiers, ESD cells are largely responsible for input bias current.
    a. Package parasitics should be considered in the datasheet specifications. For applications where very low leakage is required, care will still need to be taken in the customer's design and layout to achieve pA levels of leakage.
    4. Ib vs Vcm is shown in figure 5 of the OPA140 datasheet - again, since this represents a typical, there's not a min/max curve.
    5. Bruce Trump published a blog a while back on input bias current: e2e.ti.com/.../temperature-effects-on-input-bias-current-plus-a-random-quiz