Help with High Voltage Pulser/Receiver (until 500Volt/10ns Rise Time)

[willyp]

Hello, I'm new here.. I'm from Venezuela, and I'm doing an internship for
graduate the next year of Electronic Enginnering. My proyect is to make
generator of high voltage pulses (spikes) with rise time of 10ns or les
and pulse width variable between 100ns to 500ns... This is for connect i
to a pizoelectric transducer. I also need to make the receiver for it.

I've a basic circuit that I'm using for generates spikes of 200Voltio
with more or less 10ns rise time, but when a increment the voltage th
rise time also it grows.. so I need turn on the mosfet more quickly.. Th
basic circuit that I'm using is turn-on and turn-off a mosfet IRF840 tha
charge and discharge a capacitor through a resistor. I'm turning on th
mosfet with a pair of N and P channel Mosfet, IRF9120/IRF110.

IF somebody can help me, I'll been thankful...
My email is [email protected]

p.s.: sorry for the errors in the message, i'm still learning english



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[Winfield Hill]

willyp wrote...

Hello, I'm new here.. I'm from Venezuela, and I'm doing an internship for
I graduate the next year of Electronic Enginnering. My proyect is to make
a generator of high voltage pulses (spikes) with rise time of 10ns or less
and pulse width variable between 100ns to 500ns... This is for connect it
to a pizoelectric transducer. I also need to make the receiver for it.

What repetition rate are you seeking?

 

[Frithiof Andreas Jensen]

Hello, I'm new here.. I'm from Venezuela, and I'm doing an internship for I
graduate the next year of Electronic Enginnering. My proyect is to make a
generator of high voltage pulses (spikes) with rise time of 10ns or less
and pulse width variable between 100ns to 500ns... This is for connect it
to a pizoelectric transducer. I also need to make the receiver for it.

You might need to build a Pulse Forming Network to get the rise time. It
will need to match the impedance of the transducer, which is not trivial at
all, and the pulse width is not continuously variable. But you did not say
that you need that.

Another possibility, If the power level is not great, is avalance
transistors. Zetex makes them.

I've a basic circuit that I'm using for generates spikes of 200Voltios
with more or less 10ns rise time, but when a increment the voltage the
rise time also it grows.. so I need turn on the mosfet more quickly..

Maybe, but what You really need is more current dumped into the mostly
capacitive load and charge it faster. It is the results that count.

It is relatively easy to get/build drivers for MOSFET's that will push an
arbitrarily large current into the gate (well, limited by the max gate
voltage and the bonding wire).

Maybe you have to run from 500 V (or more) and simply clamp the voltage
across the transducer.

The
basic circuit that I'm using is turn-on and turn-off a mosfet IRF840 that
charge and discharge a capacitor through a resistor. I'm turning on the
mosfet with a pair of N and P channel Mosfet, IRF9120/IRF110.

*Use the real transducer*:

It will behave differently from a simple capacitor - specifically it will
have resonances and my bet is that the impedance will vary depending on
power level and the media it is working in.

Designing for something else than the real thing is a waste, IMO, and I
would not bother with it.