Boosting 1V amplitude square wave to 50V with rise time under 10ns.

Thread Starter

LIno22

Joined Jul 23, 2019
4
Guys i need to calibrate a Tektronix P6015a power probe, but i don't have PG506A, which can give the required 50V / 1kHz / RT<10ns.
I was thinking about boosting up a 1V/1kHz generator square wave (R&S SMT06), that has rise time under 10ns. We are talking about an amplitude (0-50V).
I used a simple one bjt stage that is triggered by the 1V square wave signal and switches 0-50V (being fed by 50VDC) on the output, but my Spice shows a deterioration of the rise time to 3us.
Some poeple mentioned that FETs can be the way out of this.
What do you think?
 

jiggermole

Joined Jul 29, 2016
161
I'm pretty sure its the propogation delay in the datasheet that determines that, right? Also the gate capacitance, the time to charge the gate up to the threshhold level feeds into that delay as well. So the generator output would have to put out enough current to be able to hard turn on the fet in a reasonable time.
So to answer you're question, I think thats a viable plan that requires some more math.
 

MisterBill2

Joined Jan 23, 2018
17,729
You will need a very fast switching transistor, probably sold as an RF amplifier device for class "C" applications. so it will not be cheap. I suggest contacting an applications engineer of a transistor manufacturer.
 
Guys i need to calibrate a Tektronix P6015a power probe, but i don't have PG506A, which can give the required 50V / 1kHz / RT<10ns.
I was thinking about boosting up a 1V/1kHz generator square wave (R&S SMT06), that has rise time under 10ns. We are talking about an amplitude (0-50V).
I used a simple one bjt stage that is triggered by the 1V square wave signal and switches 0-50V (being fed by 50VDC) on the output, but my Spice shows a deterioration of the rise time to 3us.
Some poeple mentioned that FETs can be the way out of this.
What do you think?
It's hard, because: Q = C x dU = I x dt
And not only the power supply requirement is hard, but the driving circuit (gate current).
 
Guys i need to calibrate a Tektronix P6015a power probe, but i don't have PG506A, which can give the required 50V / 1kHz / RT<10ns.
......
Some poeple mentioned that FETs can be the way out of this.
What do you think?
Hi,

Basically you would need a MOSFET or a bipolar transistor that has RT<10 ns switching specs.
These two papers could help you understand the problems involved and give hints. Unfortunately, the ultra fast MOSFETs used back then have become partly obsolete but substituting them by Silicon Carbid MOSFETs (a random example here) can solve the RT<10 ns speed. Just search for such types.

https://www.slac.stanford.edu/pubs/slacpubs/13250/slac-pub-13410.pdf

https://www.slac.stanford.edu/pubs/slacpubs/13750/slac-pub-13774.pdf

Winnie
 

Thread Starter

LIno22

Joined Jul 23, 2019
4
Hi Winnie, i have already started working on a BJT to MOSFET switch. Thank you for the transistor sheets, that will help!
 

MisterBill2

Joined Jan 23, 2018
17,729
Probably it will be an RF power device based on the rise time requirement. Although some of the inverter transistors now offered are really fast.
 
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