HF pulse generator

Hi all,

I'm looking to create a high simple high frequency (10Mhz) pulse with a low component count. Anyone know of some simple HF one-shot pulse circuits that require a small number of parts. For example, every time a microcontroller clocks a line, a quick pulse would be seen on the output. This is too high frequency for a 555, and I would like to stay away from inductors for potential production purposes, but I'm sure there's a handy single BJT circuit out there. any ideas? :o)

Thanks in advance for your help.

Best Regards, Adam Kumpf

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Adam Kumpf
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Hello Adam,

You could use a fast Schmitt trigger wired up as a differentiator. If not familiar with that look at figure 7 on the ON Semi data sheet for the MC14106B. But pick a faster chip for this application, maybe from the 74HC series. If the uC runs at less than 5V look at Schmitt tiggers in one of the fast low voltage logic series from TI. In case you'd rather take a NAND because you need some of these elsewhere, most series also offer quad NAND chips with Schmitt inputs.

Besides that one Schmitt gate you only need a resistor and a capacitor, no inductor. It doesn't get much cheaper than that.

Whatever you do, keep in mind the pulse repetion rate and whether there is any chance that the series cap might drive into the input diodes. That could be a concern, especially if the uC ports are a bit weak. Or too strong to cause latch-up.

Regards, Joerg

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Are you worrying about repetition rate or pulse length? There are at least a million options, from analog one-shots through clocked logic. I suspect I would lean towards a clocked PLA which can be very cheap, accurate, and flexible.

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