High frequency pulse generator

In summary: With this circuit, you can generate a pulse with a width of about 2.5V, 50 Ohm output impedance, and very little jitter/be stable.In summary, this circuit allows you to generate a pulse with a width of about 2.5V, 50 Ohm output impedance, and very little jitter/be stable.
  • #1
Soliton_steve
1
0
Hi,

I'm trying to build a high frequency generator. The pulse needs to have atleast 1ns rise/fall time, variable amplitude (~0-8V), 50 Ohm output impedance, and have very little jitter/be stable and I need to be able to set the pulse width and delay from ~5-1000ns.

Cheers,

Steve
 
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  • #2
Yes, I'd like one of those too.

In principle, you turn on a gate to give 5 volts out. Then you count pulses from a clock for the required pulse time and then you turn off the gate. Then you count a different number of pulses from the clock to get the delay time before you turn the gate on again.

However, you would have problems getting suitable chips to do it.
Taking your extreme values, 5 nS on 5 nS off, that is 100 MHz which means your clock speed would be at least 200 MHz to get two rising edges in a 5 nS pulse. There are not a lot of chips that can do programmed counting at a 200 MHz clock rate.

Then you need to control the counter to get the right number of counts and you need to display this somehow.

Such an instrument could be developed given $50000 or bought for about $5000 if one already exists. See Agilent (HP). They have some nice function generators.

If your requirements were not really that stringent, maybe you would like something like this:
http://alternatezone.com/electronics/hsfg.htm
 
  • #3
vk6kro said:
Such an instrument could be developed given $50000 or bought for about $5000 if one already exists. See Agilent (HP). They have some nice function generators.
Hmm that's a little high for a 200MHz pulse generator.
http://www.google.com/products?q=pulse+generator+250+Mhz&hl=en
This pops up quickly
http://www.bellnw.com/products/1210/ [Broken]
 
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  • #4
Yes, second hand would be a good way to go. Note that the $34 and $53 ones were just books, not the instrument.

But it looks like you could get something useful for about $200 without even having to bid for it.
Like that
TEKTRONIX PG 502

You might also like to read this thread from June 22nd:
https://www.physicsforums.com/showthread.php?t=321383
Several nice instruments were located but were expensive if bought new.
 
  • #5
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  • #6
That's more like the prices we were getting before. $10000 to $16000.

Waht, are you in Australia? Where?
 
  • #7
vk6kro said:
That's more like the prices we were getting before. $10000 to $16000.

Waht, are you in Australia? Where?

I'm in the US.

The cost of good test equipment in general could be a down payment on a house.
 
  • #8
Here is a freely available service manual of HP 8012B pulse generator with circuit description and schematics.

It's 46 mb in pdf, and is an informative reference

http://bama.edebris.com/manuals/hp/8012b/
 
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  • #9
waht said:
some of these pulse generator in the link going for $600 up are at least 30 years old,

you could probably find a good HP 30 year old for half that on ebay,


Here is modern pulse generator:

http://www.home.agilent.com/agilent/product.jspx?nid=-536902258.536881947.00&cc=US&lc=eng
Well that's a pattern generator, different beast. Also, this is the usual 'system' based gear - a full blown computer system w/ 488 remote control, 'SRAM adapter cards', blah, blah, and it happens to have a pulse generator along for the ride.
 
  • #10
If you were prepared to experiment a bit, there is a more crude way of getting short pulses.
I invented this years ago and find it very useful.

If you take a NAND gate and apply a square wave to one input directly and to the other input through an integrator, you get a downward going pulse at the output that depends, in width, on the time constant of the integrator. It starts at the rising edge of the input square wave.

The integrator can be just another NAND gate with the input pins tied together, a series resistor to the input of the NAND gate and a capacitor from output to input. Just like an OP amp.
You can make the resistor variable for variable pulse width and switch capacitors for bigger steps in pulse width.

If you take the output of this pulse generator and pass it through an inverter (which can be another NAND gate with the inputs tied together), you have a positive going pulse that repeats at the same rate as the square wave, but variable up to the period of the positive part of the square wave.

You do not get a pulse off the falling edge of the square wave with this arrangement.
 
  • #11
I suspect you will want to use discretes rather than logic arrays for your outputs. Do you know what style of output you want; NPN vs PNP, collector outputs (best for current sources) or emitter followers? Any particular circuit, like (common emitter) differential pair for example?
 

What is a high frequency pulse generator?

A high frequency pulse generator is a device that produces electrical pulses with a high repetition rate, typically in the range of 1 MHz to 40 GHz. These pulses can be used in a variety of applications, such as in medical devices, telecommunications, and scientific research.

How does a high frequency pulse generator work?

A high frequency pulse generator works by using electronic components, such as transistors and capacitors, to rapidly switch the flow of electric current on and off. This creates short bursts of electrical pulses at a high frequency, which can then be used for various purposes.

What are the benefits of using a high frequency pulse generator?

Using a high frequency pulse generator offers several benefits, including the ability to generate precise and controlled pulses at a fast rate, the ability to vary the pulse width and amplitude, and the ability to produce pulses with a high signal-to-noise ratio. This makes it useful for many scientific and technological applications.

What are some common uses of a high frequency pulse generator?

A high frequency pulse generator has a wide range of uses, including in medical equipment for diagnostic imaging, in radar and sonar systems for detection and ranging, in telecommunications for signal processing, and in scientific research for studying the properties of materials and electronic devices.

How do I choose the right high frequency pulse generator for my needs?

When choosing a high frequency pulse generator, it is important to consider factors such as the frequency range, pulse width and amplitude capabilities, and the specific application for which it will be used. It is also important to consider the reliability and accuracy of the device, as well as any additional features or specifications that may be necessary for your specific needs.

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