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OPA2180: Points to be aware of when using and selecting Laser Trim, e-Trim, and Chopper

Part Number: OPA2180
Other Parts Discussed in Thread: OPA191, OPA192

Hi,

I read the following documentation, but didn't know which offset correction technology to choose when choosing a device with a low offset.

"Offset Correction Methods: Laser Trim, e-Trim, and Chopper"

https://www.tij.co.jp/jp/lit/an/sbot037c/sbot037c.pdf

Please tell me if there are any points to be aware of when using and selecting Laser Trim, e-Trim, and Chopper.

Thanks,

  • Hi Koki,

    this mainly depends on how much offset voltage you can tolerate in your circuit.

    Kai

  • Hi Kai,

    Are the Laser Trim, e-Trim, and Chopper roughly different in their ability to remove offset voltage? Please tell me which technology can be removed and how much. It seems that this is not mentioned in the documentation.

    Thanks,

  • Hi Koki-san,

    Please tell me if there are any points to be aware of when using and selecting Laser Trim, e-Trim, and Chopper.

    If you are concerned about op amp's input offset voltage, it is the best to compare the datasheet or  performance of interested op amp products. 

    Laser trim is typically a wafer-level trim, E-trim may be wafer-level trim or post package-level trim. Chopper amplifier is a dynamic correction technique used in zero-drift amplifier. All three offset correction methods can effective reduce the offset voltage, but there are pro and cons in each technique, see the captured table below. 

    When a Si die is encapsulated in a molding compound, the internal physical stress from curing of epoxy molding compound can create additional shift in the offset voltage, even after a wafer-level trim has been performed. Therefore, the best option is to perform a post package level trim or e-trim method (after a Si die is encapsulated) to reduce overall offset voltage in a package (e.g. OPA192, OPA191). 

    Chopper amplifier has low offset voltage and lowest offset voltage drift, but it has disadvantage in the spectrum domain at a chopper frequency, which prior two Vos correction methods do not have. The low offset in chopper amplifier is a side benefit from dynamic correction of the input offset voltage drift method. 

    There are no one solution for in selecting various op amp based on the trimming technique for a given applications. Thus, it is important to understand the design/application requirements and select/compare proper op amps according to the requirements from an op amp's datasheet, performance and/or simulation etc.. 

    Best,

    Raymond