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I need to deliver a 40 V (minimum), 4.25 MHz, sine wave to a PZT transducer (medical ultrasound application). I have explored trying to use a dc/dc step-up with a switch, but this will only give me a square wave as I understand it. Furthermore, I have tried to search oscillators but most give within the range of 1-3V outputs and as we all know, op-amps can't output more than their supply voltage an I'm trying to stay away from directly supplying 40V to a single element of my circuit. Any suggestions would be greatly appreciated as I feel I have hit a dead end.

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    \$\begingroup\$ How much power do you require at the output? \$\endgroup\$ – Richard the Spacecat Mar 13 '18 at 14:24
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    \$\begingroup\$ nearly all medical ultrasound imaging uses on/off switches, what's wrong with that? \$\endgroup\$ – user3528438 Mar 13 '18 at 14:25
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    \$\begingroup\$ And: you want to generate 40V, but you don't want to deal with supplying 40V for your components? I have bad news for you... \$\endgroup\$ – Marcus Müller Mar 13 '18 at 14:27
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    \$\begingroup\$ XY problem smell \$\endgroup\$ – Andy aka Mar 13 '18 at 14:42
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    \$\begingroup\$ "I have explored trying to use a dc/dc step-up with a switch, but this will only give me a square wave as I understand it" A square wave's fundamental frequency can be filtered to produce a sine wave. \$\endgroup\$ – Norm Mar 13 '18 at 15:07
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Use 2 opamps, the first opamp is inverting, as is the 2nd opamp; first opamp has gain of -10, thus 1vpeak becomes -10 volts peak output; the 2nd opamp exactly (as exact you can get at 4.25MHz) inverts the first opamps -10v output to produce +10v peak. Now connect the piezo between the 2 opamp outputs.

Driving the first opamp with +-1v peak, will produce +- 10v peak from each opamp, and the complementary drive produces +-20 volts peak, or 40v peakpeak.

Now about an opamp to fairly accurately produce 10 volts at 4.25MHz: you will need a slewrate of 10v * 4.25 * 2 * PI === 240 volts/uS slewrate.

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If that's for a single pulse, you can use off-the-shelf components. As a pulser, you could use:

  • NMT0572SC for high voltage generation from 5V
  • TC6320TG for pulse production (you still need to supply it with High Voltage), using a MD1213 for control
  • Protect the rest of the design with a MD0100

And you have yourself a nice pulser board!

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