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OPA277 AMPLIFIER

akhilesh sati
Intellectual 950 points

Other Parts Discussed in Thread: OPA277

 I am in a situation where  I am using TI's OPA277 with dual power supply then it is giving proper, BUT when it is being used with single power supply its gain is getting reduced. why it is so? 

regards

Akhilesh Sati

  • 0
    Guru 21975 points

    Akhilesh,

    When used properly, there will be no difference in gain when operated with a single power supply. The link below may help explain input and output voltage range limitations that usually are the source of problems with single supply operation.

    Op Amp Voltage Ranges—input and output, clearing some confusion

    If you continue to have problems, please provide a schematic with details on supply voltage, signal conditions and your method of measuring gain.

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Intellectual 950 points

    Dear Sir,

                   I am uploading both schematics.in first case i have taken +5V and -5V power supply for op-amp and gain is around 100. bot if connect this op-amp with +10V and GND, for the same applied input and feedback ,rather than getting amplified signal at the output i am getting attenuated version of input signal at the output. why this is so?

    regards

    akhilesh

  • 0 in reply to akhilesh sati
    Guru 21975 points

    Akhilesh,

    The input common-mode range of the OPA277 must be at least 2V above the negative rail voltage. (See the specifications for the OPA277 with regard to input common-mode range.) You have the non-inverting input connected to ground with a single power supply. The OPA277 cannot operate in this voltage condition.

    Please read the article in the link I provided in my first message as this will help explain the issue. Pay particular attention to the discussion of input common-mode range.

    You could try the same circuit with an op amp such as the OPA234 which is designed for single supply operation.

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Intellectual 950 points

    Thank you sir for your response and guidance.

    regards

    Akhilesh Sati