Hello i need to convert a 0-3.3V 120ns 500ns period pulse into -2v to -5V pulse to turn on and off CGHV1A250F.
I got the circuit shown below ,but its very odd.
I need to control the upper level lower level and keep the output pulse as square as possible.
Is there some new circuit configuration you could reccomend me to use instead the circuit i got?
Thanks.
https://pdf1.alldatasheetde.com/datasheet-pdf/download/1673867/WOLFSPEED/CGHV1A250F.html

 

Several questions first: How much current do you need at each of the desired output levels? Those are fairly fast pulses, or I would suggest an op-amp That would be the very simplest way to do it if you can find a fast enough one.
I am not familiar with the CGHV1A250F. but there are driver ICs available that are really fast and can deliver enough current.

 

Hello mister bill the rise falls time is 10ns
The voltage level switches between -2 and -5 , Cgate =100pf I=CdV/dt

How can I implement such circuit with opamps?
Thanks .

 

Hello mister bill the rise falls time is 10ns
The voltage level switches between -2 and -5 , Cgate =100pf I=CdV/dt

How can I implement such circuit with opamps?
Thanks .

Unfortunately, as IT IS a signal to turn on a MOSFET , it will require a gate driver , not an op-amp. And at that point others are probably more current in their current parts knowledge.
If you can get to the manufacturer's website they may have applications literature and suggestions for drivers.

 

The output shown can certainly be accomplished nicely with the selection of an appropriate op amp.
Mosfets often need gate drivers and noted for specific applications
With op amp oscillators in general, the split supply can be individually set for both positive and negative supply rails relative to virtual ground,

Op amp then Transistors. Text books teach progressively starting with simple transistors circuits then op amps, experience gives you a feel.
In design we understand the quantitative approach, selecting the right tools, skillful in using approximation and bench techniques.
In this case possibly using a more flexible approach initially would help determine the constraints for a dedicated transistor circuit.

I see such projects implemented first in Ltspice that include a split supply and on page connectors for better clarity.
Having the source in a separate section simplifies giving structure to the schematic. Each of the elements in the schematic layout
should convey what each circuit element in schematic as close to conventional standards as possible.

 

Hello i need to convert a 0-3.3V 120ns 500ns period pulse into -2v to -5V pulse to turn on and off CGHV1A250F.
I got the circuit shown below ,but its very odd.
I need to control the upper level lower level and keep the output pulse as square as possible.
Is there some new circuit configuration you could reccomend me to use instead the circuit i got?
Thanks.
https://pdf1.alldatasheetde.com/datasheet-pdf/download/1673867/WOLFSPEED/CGHV1A250F.html
View attachment 324353

View attachment 324354

How about an optocoupler?

https://forum.allaboutcircuits.com/threads/using-transistor-optocoupler-for-level-shifting.181187/

 

The output shown can certainly be accomplished nicely with the selection of an appropriate op amp.
Mosfets often need gate drivers and noted for specific applications
With op amp oscillators in general, the split supply can be individually set for both positive and negative supply rails relative to virtual ground,

Op amp then Transistors. Text books teach progressively starting with simple transistors circuits then op amps, experience gives you a feel.
In design we understand the quantitative approach, selecting the right tools, skillful in using approximation and bench techniques.
In this case possibly using a more flexible approach initially would help determine the constraints for a dedicated transistor circuit.

I see such projects implemented first in Ltspice that include a split supply and on page connectors for better clarity.
Having the source in a separate section simplifies giving structure to the schematic. Each of the elements in the schematic layout
should convey what each circuit element in schematic as close to conventional standards as possible.

OK, Sparky, and yes, with the suitable op-amp it could be done, but I am not in a position to suggest the right one.
And I am leery of simplifying things too much, which often leaves out the part of the circuit that we need to see what is actually happening.

 

Hello ,The issue with such circuits that in order to pass the pulse i need to use transistors with as higher bandwidth as possible.
What higher BW BJT you could reccomend me to improve the shape of the output ?
Also i was told that putting the BJT into saturation makes its BW smaller? is it true?
Thanks.

 

What higher BW BJT you could reccomend me to improve the shape of the output ?

It's not transistor bandwidth per se, that you want, but one specified for fast saturated switching.
For that, you need one that has a low saturation delay, such as the NPN 2N2369 or the PNP 2N5771.
General purpose transistors have a significant delay coming out of saturation, which limits their switching speed.

 

Absurdly High-Frequencies are very complex, there is nothing that is standard or basic about them.

I would suggest that You talk to the manufacturer and see if they have recommended Schematics
for creating what ever your project may be.
I'm guessing that it's a Radar-System of some sort.

If You have to ask how to do it .............
Every single Component, and each Component's relationship to every other Component,
is probably too critical for You to achieve success with a DIY Project.
.
.
.

 

I would think that you could do what you want using an LT1364 op-amp – it has a 70MHz bandwidth with a 1000V/µs slew rate.

The data sheet lists rise/fall times of <4ns; bear in mind these will be for small voltage changes, but nonetheless with careful circuit design you should be able to achieve <100ns for larger voltage swings.

The data sheet includes oscilloscope traces rise and fall times.

 

Really, it may be useful to investigate some of the microwave transistors. "Minicircuits" is a company that produces a lot of devices that operate in the medium gigahertz range, and to keep square edges yuo do need a much higher frequency response. in every component.