High voltage nanosecond pulse generator

[kender]

nanosecond pulse generator

Colleagues,

Could anyone suggest a schematics or a reference for a high voltage pulse generator? I need a 500V pulse 10ns long or sorter. Negative spike from 500V to 0 and back to 500V would work. I have a schematic for an old (1977) pulser, but the SCR that's used there has been discontinued. I know how to generate a nanosecond pulse at the logic levels. But what would be a good topology for the high voltage "switch"? MOSFETs have gate capacitance that needs to be charged within a few nanoseconds. SCRs (which I, unfortunately, don't have experience with) have their own problems too.

Enlightenment will be appreciated!

- Nick

 

[Faizan Jawaid]

avalanche pulse generator

SCRs can do u the job...But ur freq is too high...Why do u need that kinda pulse? generating ur own noise ?

 

[drabos]

pulser

what about avalanche transistor

 

[FvM]

pulse generator circuit avalanche

You should also specify a load impedance and intended risetime.

For moderate specifications, MOSFET would be first choice, I think. The voltage level can achieved without cascaded switches, which is important to reduce the control effort.

The said avalanche transistors can only generate a single fast edge, they could be used in a cable pulser circuit to form rectangular pulses.

For lab purposes, a mercury wetted reed relays can achieve up to 1 kV pulses with 0,2 ns rise time. But the repetition rate is limited to a few 100 Hz and a high jitter is observed, so the trigger must be from the pulse itself. It's mostly used in a cable pulser circuit.

 

[ESDSolutions]

hv pulse generation with fet

Hello

You can get a solid-state pulse generator from Avtech (https://www.avtechpulse.com/) They have all sorts of models including for 500V and 10ns pulse width. They can even build a custom one if needed. Even load and pulse impedance can be set.

Check their online search tool (https://www.avtechpulse.com/pick/).
Cost is mentioned but expect something in order of $10k to $20k.

If you really want to make this yourself you can build it using a fast relay and one meter of coaxial cable. I suppose that you want a 50 ohm environment. People in the ESD field have been building so-called 'Transmission Line Pulser' or TLP equipment. Basically the cable represents a capacitor. You charge up the capacitor to a specific voltage. Have used this up to 10kV in the past. Then a relay is used to connect the "capacitor" to the device under test. when you have a perfect matched circuit you will get a nice square pulse.

- Rise time of 2ns is easy to do with std relay and RG58 coax. If you need shorter rise time special cable and more expensive relay is required.
- pulse width is set by coax length

Check out following publications:
- **broken link removed**
- **broken link removed**
- **broken link removed**

Good luck building!

 

[kender]

pulse generator nano second high voltage

You should also specify a load impedance and intended risetime.

The load impedance will be 50 Ohms. Fall time time, probably around 3-5ns.

For moderate specifications, MOSFET would be first choice, I think.

What would drive the gate with?

SCRs can do u the job...But ur freq is too high...Why do u need that kinda pulse? generating ur own noise ?

The big problem is to identify an SCR or a MOSFET+gatedriver that can do this job. After that, I can start experimenting. Could you post a model of an SCR that can do it at my rise time?
I'm designing this pulser to “whack” a piezo transducer with a Dirac function to make it ring.

 

[FvM]

pulse generator nanosecond kv

What would drive the gate with?

With fast bipolar transistors, designed for RF power amplifiers. Selecting a suitable MOSFET is the most critical point. I have been designing a 500V, 4 ns pulser with vertical DMOS FET, but for a lighter capacitive load. A n-fold parallel circuit would be needed to drive a 50 ohm load.

Most commercially available ns/kV pulsers are using MOSFET or avalanche BJT, but it's far from an easy design.

 

[rauol]

nano-second pulse generator

you can try using high voltage RF mosfets from APT( now Microsemi) they have 500V RF Mosfets with high speed switching speeds.

 

[kender]

voltage pulse + mosfet

Just two potentially useful links:
A web site with lots of DIY high voltage projects **broken link removed**
An article on a cascode MOSFET topology for a nanosecond high voltage pulse generator:
UPDATE: I've ended up buiding a cascode switch similar to this one and it had satisfied my needs.

 

[detonator]

Re: voltage pulse + mosfet

Just two potentially useful links:
A web site with lots of DIY high voltage projects **broken link removed**
An article on a cascode MOSFET topology for a nanosecond high voltage pulse generator:
UPDATE: I've ended up buiding a cascode switch similar to this one and it had satisfied my needs.

Both of the links are not correct.

---------- Post added at 17:08 ---------- Previous post was at 16:43 ----------

You should also specify a load impedance and intended risetime.

For moderate specifications, MOSFET would be first choice, I think. The voltage level can achieved without cascaded switches, which is important to reduce the control effort.

The said avalanche transistors can only generate a single fast edge, they could be used in a cable pulser circuit to form rectangular pulses.

For lab purposes, a mercury wetted reed relays can achieve up to 1 kV pulses with 0,2 ns rise time. But the repetition rate is limited to a few 100 Hz and a high jitter is observed, so the trigger must be from the pulse itself. It's mostly used in a cable pulser circuit.

can someone recommend a mercury wetted reed relay which can generate 600V 10ns pulser?