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I am designing a single stage driver circuit that needs to be capable of driving a rectangular pulse wave up to voltages of +50V. The slew rate has to be at least 500 V/μs. So far, I have found 2 op amps that meet these criteria: the MSK613 and MSK600. Here is the datasheet for the MSK613: https://cdn.anaren.com/product-documents/MSK/Amplifiers/MSK613/MSK613_DataSheet(Rev_B).pdf

However, the manufacturer does not want to sell these to my research group, so I am looking for alternatives that are as powerful. Any advice on how to design an alternative driver circuit would also help.

Thanks

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    \$\begingroup\$ If it's a rectangular pulse why are you using an op-amp? \$\endgroup\$ – DKNguyen Jun 24 at 21:12
  • \$\begingroup\$ Since you have defined NO LOAD: no resistor, no capacitor, no inductor, and you have provided NO PRECISION required, and no limitation on ringing, this is easy. \$\endgroup\$ – analogsystemsrf Jun 25 at 3:02
  • \$\begingroup\$ @DKNguyen I am new to amplifier design, what would your suggestion be? \$\endgroup\$ – Alex Novytskyy Jun 25 at 22:46
  • \$\begingroup\$ @analogsystemsrf The load is purely resistive. As for precision, we want the output wave to have the same phase as the input with (ideally) no slew. \$\endgroup\$ – Alex Novytskyy Jun 25 at 22:47
  • \$\begingroup\$ @AlexNovytskyy dont use an amp. use a half bridge or a totem pole or a push-pull \$\endgroup\$ – DKNguyen Jun 26 at 0:44
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You don't need an operational amplifier to transfer a square wave. Instead, a CMOS pair would be the way you do it.

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Apex Microtechnology has some good high voltage, high slew rate op amps.

If you only need to drive a square wave though, you can probably get away without using a specialized high voltage op amp. You can use a half-bridge gate driver with a floating high side driver, like TI's LM5109A or SM74104. You would use it to drive two N channel MOSFETs in series that would switch between a fixed positive voltage rail and ground, essentially giving you a square wave output. It should have no problem going from 0V to 50V in 100ns. This is essentially a buck converter (with synchronous rectification) without the output LC filter.

If you need to switch between a positive rail and a negative rail, you should use an isolated half-bridge gate driver, which is similar to a regular half-bridge gate driver, but the outputs are isolated and tied to sources of the MOSFETs they are driving. You would need isolated power supplies.

One thing to be aware of when using a half-bridge design is shoot-through current. This occurs when both MOSFETs are conducting at the same time, essentially shorting V+ to ground, which can damaged the transistors. As long as there is adequate dead time between the high side turning off and the low side turning on (and vice versa) you will be OK.

You might be able to find a evaluation board for a half-bridge gate driver that will do exactly what you need if you dig around.

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  • \$\begingroup\$ Thanks for the help. I am still new to driver circuit design so I will have to look into half-bridge gate drivers, but I believe we will only be doing square pulses for now so it could definitely work. \$\endgroup\$ – Alex Novytskyy Jun 25 at 22:42

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