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Using LOG114 for FET testing

Jacques Lefebvre
Prodigy 10 points
Other Parts Discussed in Thread: LOG114EVM, LOG114

I would like to feed a FET current to the input of the LOG114EVM. However, I'm concerned about grounding issues that might arise from the two voltage sources I use to drive the transistor (Vds and Vgs).

Thanks,

Jacques

  • 0
    TI__Guru* 93105 points

    Hello Jacques,

    The LOG114 inputs are intended to be driven by a current. The voltage at the inverting I1 input, for example, will be at approximately the same voltage as the common-mode voltage (VCM) level applied to the log amplifier non-inverting input. That voltage will be the +2 V VBIAS level described in the LOG114 EVM document. How ever you configure your FET test circuit the FET node connected to the inverting input will be at the same potential as the VCM level. Therefore, you must plan the voltages applied to the other FET terminals accordingly.

    Regards, Thomas

    PA - Linear Applications Engineering