transform GHz to MHz so I can use my Oscope

Hi,

I have an oscope that can operate at up to 100 MHz.

My situation is that I want to measure the voltage magnitude of a signal that could have a frequency up to 1GHz, this is not a square wave shape, it is probably more like a sign wave shape.

So I am thinking that I could accomplish this by using a frequency divider to shift the GHz frequency to a range (MHz) that my oscope could handle.

Are there any big reasons why this would not work?

--TIA, jw

The OP would have to provide quite a bit more information to get a recommendation for a homebrew circuit, like frequency range of interest, amplitude range, and impedance. Also, how would he check the results from any homebrew circuit, especially if amplification/buffering was required?

It might be best for him just to do the job right and scrounge an RF voltmeter to make the measurement. They're commonly available used/reconditioned, and not very expensive. Some require special probes, so the OP should do his homework before buying.

Chris

Others have told you why that won't work. Here is one that will.

You need to build an RF mixer to get the spectrum of interest to a frequency below 100 MHz.

There are readily available VCOs and Balanced Mixers built for 1 GHz. Also, you should put a (100 MHz.) low-pass filter at the output of the mixer to eliminate the unwanted mixer product and to reduce the VCO Carrier leakage amplitude. With only a little care, the signal will be an excellent representation of it's form at 1 GHZ.

Don

Frequency divider are only useful for a frequency counter, where you don't care the shape of the signal... I think you have to buy a new scope...

Kubiack

jw a écrit :

As others have noted, frequency dividers are typically digital devices that don't preserve amplitude. But if you just want to monitor the level of the signal (not it's wave shape) you can rectify and low-pass filter it and feed the DC to your scope. No, I don't have any handy GHz rectifier circuits handy... anyone else?

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

Thanks, this is great! --jw

it

divider

frequency

Also,

I'll try a few things and get back if I run into trouble. thx, jw

signal

shape, it

divider

handle.

yes, frequency dividers typically convert the output to a fixed voltage, not proportional to the input.

A better move may be to use a downconverter (but that's about the limit of my knowledge of things RF)

Bye. Jasen