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Original question:

THS3091: Oscillation on rising and falling edge

THS3091: 1V gap on output

Damien_Effi
Intellectual 555 points
Part Number: THS3091


Tool/software:

I connected a PWM GPIO to the input and connect the output to a 50R oscilloscope input:

When the PWM (70KHz) is falling done (falling edge from 3V3 to 0V), I have a 1V gap for 50nS. Do you know where it is coming from?

Note I have the same issue if if I connect or not  the scope on the F_50R. So it looks, the gap is done internally by the THS3091.

Yellow is TP8

Green is PWM GPIO

Blue is F_50R connected to a 50R scope input.

This one is when the output is not conned to the scope

This one is the screen shot when the ouput is connected to a 50R scope input.

Thanks

Regards,

Damien

  • 0
    TI__Genius 17105 points

    Hi Damien,

    That is an interesting result you are getting. I was wondering if you would be able to maybe switch the gain to a higher gain just to debug the circuit. Would you be able to maybe try a gain of 2V/V using a 1.2k Rf? This would put the device in a known configuration so we can rule out the gain configuration it is currently in. I was also wondering if you were probing the input signal directly at the non-inverting input (left pad of R55)? This will ensure we are comparing the most accurate input signal going into the device.

    Best Regards,

    Ignacio

  • 0
    Guru 48395 points

    You don't show your supply voltages, if perhaps you are sitting saturated at the output initially, that gap is the overdrive recovery time, try to stay linear with enough supply headroom for the amplifier