Rise time measurements counter/timer vs Oscope?

Hi,

I am trying to measure the rise time of a 10 MHz square wave with a Keysight 53220A universal counter. The source has a specified rise time at 10 MHz of <3 nS. This is confirmed to be about 3 nS when measured on a scope.

However, when measured on the counter I am seeing a rise time of around 40 nS (10-90%).

I suspect that either I am not measuring the same thing or I may be setting up the measurement incorrectly on the counter. (the user manual has very little on this).

Any help or suggestions would be appreciated.

Thanks,

Mark

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0 Jan Cumps over 3 years ago

Is the 10/90% on the counter rise time or duty cycle?A sking because the UOM is %, and that's more common for the duty cycle.

2nd check: input impedance of scope vs counter. Are they both 50 Ohm, both high impedance, or is one different from the other?
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0 dc2daylight over 3 years ago in reply to Jan Cumps

Ok, yes, It's a time interval parameter, not a duty cycle.

My understanding is the 10-90% is the time interval it takes the signal to go from 10% to it's final value of 90% of it's final value.

It is an adjustable parameter but I thing the 10/90 is most commonly used.

Using 50 ohms input impedance on both.
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0 dc2daylight over 3 years ago in reply to Jan Cumps

Ok, yes, It's a time interval parameter, not a duty cycle.

My understanding is the 10-90% is the time interval it takes the signal to go from 10% to it's final value of 90% of it's final value.

It is an adjustable parameter but I thing the 10/90 is most commonly used.

Using 50 ohms input impedance on both.
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0 Jan Cumps over 3 years ago in reply to dc2daylight

dc2daylight said:
I thing the 10/90 is most commonly used

Yes, you are correct.
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