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Original question:

OPA4277: opa4277 analog

OPA4196: OPA4196 with booster

Vladimir Naumenkov
Expert 2970 points
Part Number: OPA4196
Other Parts Discussed in Thread: BUF634A

Dear Thomas, please answer

I decided to use booster with OPA4196. I need to increase output current. Please, see my circuit in attach. 

VG1 - is the DAC with output voltage from 0 to 3 V, then I set a shift at the "+" input  of the amplifier. 

How do you think, will this circuit work?

TIA

Sincerely,

Vladimir Naumenkov

OPA196 boost_2.TSC

  • 0
    Guru 48395 points

    You are using a class B transistor output stage, that will open up on 0 crossover opening the loop transiently - not a good thing, It appears you are trying to produce a +/-34mA into that 200ohm load, surely there is a device that will do that directly. 

  • 0
    TI__Guru* 93105 points

    Hi Vladimir,

    Michael's point about the class-B output buffer is a true concern. There are techniques seen on line for adding circuitry to the class-B output to change its operation to class-AB. However, the complexity of the circuit and the number of components increases.

    An alternative approach is to add a high-performance, high-fidelity, open-loop buffer after the OPA4196 output. The BUF634A from TI's High-Speed Amplifiers group is such a device. You can see the datasheet here:

    http://www.ti.com/lit/ds/symlink/buf634a.pdf

    You will be able to maintain the high-performance of the OPA4196 using this approach. However, do take into account that 100 nF cap load. That may create a stability problem with many op amp circuits. Compensation may be needed to assure stability.

    Regards, Thomas

    Precision Amplifiers Applications Engineering