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OPA134: OPA134 showing strange output.

Dylan O
Prodigy 195 points
Part Number: OPA134

I have a opa134 soldered into a simple non-inverting opamp circuit shown below.

Input is 1Vp-p. The output is severely distorted unless the supply rails are increased to +/-15V. The datasheet says it can take +/-2.5V minimum.  What am i missing?

  • 0
    TI__Guru* 93105 points

    Hello Dylan,

    You don't mention in the input voltage amplitude being applied to J1. You have the OPA134 set up as a non-inverting amplifier which exercises the input Common-Mode Voltage Range (Vcm) of the Op amp. For the OPA134 the linear input Common-Mode Voltage Range is specified from (V–)+2.5  to (V+)–2.5 V. Therefore, with +/-5 V supplies the Vcm range is approximately -2.5 V to +2.5 V. If those limits are exceeded the Op amp input stage is forced into non-linear operation and distortion will occur. You also need to make sure that the specified output voltage range isn't being exceeded as well.

    Increasing the supply voltages increases the Vcm range and linear operation will be obtained provided the input signal's common-mode voltage stays within that range. Try reducing the input signal level and see if the distortion drops off. 

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 195 points

    Thanks for the reply, i discovered it was a soldering/wiring issue.