i should measure very fast changing signal with ADC, but ADCs has very narrow input voltage range at the high frequencies,
signal peaks i need to measure is between 10V to -5V. Signal looks like on the following photos.
it needs ADC like around 30mhz i guess, and they can not measure wide analog input ranges. they measure 2V input range . I thought to use opamp voltage scale, would it be accurate enough, to zip voltage to 1V?
would you suggest any other method?
for sure you can use a 30MHz sampling ADC. You can try to divide the voltage with a simple divider, or you may use an Opamp as buffer.
But maybe you don´t need that..
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I often get jobs like this, then I find out the there are more simple solutions to come to the same result...therefore:
What is your goal?
* counting pulses?
* measure the amplitude of the pulse? (What amplitude: every single peak, an average of some pulses, the highest peak in a period of time...)
* you want to analyze the wavefrom? (like FFT...)
* calculate something else...
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The waveform (timing) looks very random... where does it come from?
What impedance is the signal?
What precision and what resolution do you need? How to verify this?
it is voltage drop on an inductor.
i used a voltage scale with 3 resistors. pulled to voltage between 0-2V. and used 40mhz as you suggested.
the to measure voltage drop on the inductance during switching the semiconductor.
In general, reducing resolution, increases speed, and vice-versa. Without seeing in detail the requirements above, a possibility to be considered, and it is even adopted in some equipment to make reading beyond the maximum speed of the A/Ds, is by utilizing multiple converters in parallel, each of which performs sampling at intercalated intervals. I presume would be required to perform a post processing in order to calibrate the overal reading process, compensating differences on each convertor. In
How can you say that? Your scope picture with the peaks says something completely different.
I see 8us, 20us, 50us, 82us.... it has nothing to do with 1kHz.
when the circuit comes, it wil work with 1 khz,
but on the simulation, i switched the igbt on different times, unabhangig from 1khz.
actually diL/dt and dic/dt is same, because
IC =collector current, dic/dt = increase rate of the collector current,
IL = current of the parasitic inductance.
IC = IL,
i hope i could explain better.
actually i am done with this, i made a voltage scale to have 0-2V and used 40MHZ adc.
best regards