Op-amp/ frequency scale question

[Jason_TTU]

Hello, im trying to scale up a frequency in the 40-80hz range up to a range higher then 5Mhz. Taking a shot in the dark I think I need to use a op-amp with an high gain. I have a MC3403P op-amp that has a 9 MHz Bandwidth. The data sheet can be found here. https://www.fairchildsemi.com/ds/MC/MC3403.pdf
My question is how I can use this op-amp to increase the frequency above 5 MHz or what is a simple way to increase a frequency.

 

[Nigel Goodwin]

It's nothing an opamp could do, but you really need to explain EXACTLY what yo're trying to do - generally if something sounds as silly as this, it's because the original premise is completely wrong.

 

[Optikon]

Hello, im trying to scale up a frequency in the 40-80hz range up to a range higher then 5Mhz. Taking a shot in the dark I think I need to use a op-amp with an high gain. I have a MC3403P op-amp that has a 9 MHz Bandwidth. The data sheet can be found here. https://www.fairchildsemi.com/ds/MC/MC3403.pdf
My question is how I can use this op-amp to increase the frequency above 5 MHz or what is a simple way to increase a frequency.

Are talking about generating 5MHz ? Or amplifying at 5MHz? Or something else? Your MC3403 will have very little gain left @ 5MHz.

 

[evandude]

It sounds like what you are trying to build is a mixer:
https://en.wikipedia.org/wiki/Frequency_mixer
Op-amps amplify voltages/currents, you can't "amplify" a frequency - mixers use non-linearity to achieve multiplication to shift a signal in frequency.

As nigel said, you should post a lot more info about exactly what you're trying to do. Given your original post, I think implementing a system with a mixer might be a bit challenging.

 

[audioguru]

Look at the datasheet.
The MC3403 has full output up to only 9kHz, not 9MHz. Its gain at 1MHz is only 1 and is less at higher frequencies, but its output cannot swing at high frequencies.

It is a low-power version of a lousy old 741 opamp, but it doesn't have the crossover distortion of a lousy old LM324.

 

[Jason_TTU]

Thank you guys for your help. What im trying to do is build a light intensity to frequency converter. I used a voltage to frequency converter. The chip number is k4331 and the data sheet can be found here. https://www.electro-tech-online.com/custompdfs/2007/04/KA331.pdf
I built the circuit shown in figure 3 of the data sheet. This circuit works great and gives me a pulse train out with frequency proportional to the light intensity. My output is between 40 and 80Hz depending on the amount of light I let hit the phototransistor. What I want to do is increase this output somehow to be in the 5+ Mega Hz range

 

[Optikon]

Look at the datasheet.
The MC3403 has full output up to only 9kHz, not 9MHz. Its gain at 1MHz is only 1 and is less at higher frequencies, but its output cannot swing at high frequencies.

It is a low-power version of a lousy old 741 opamp, but it doesn't have the crossover distortion of a lousy old LM324.

I didnt look. The OP said it was 9MHz.. the OP isnt even posting clear questions. I doubt he'll post back anyways..

 

[Jason_TTU]

I didnt look. The OP said it was 9MHz.. the OP isnt even posting clear questions. I doubt he'll post back anyways..

The reason why I posted that the op-amp was 9MHZ was because that was the information on mouser.com said when I bought it. Here is the link. https://www.mouser.com/search/ProductDetail.aspx?R=512-MC3403P
I guess there’s a typo somewhere.
Thank you,
Jason

 

[Papabravo]

Rather than trying to convert one frequency to another you might be better off thinking about a VCO. That a voltage controlled oscillator. There are lots of circuits available for that frequency and several different ways of deriving the control voltage.

If I have a choice between trusting a distributor and trusting the manufacturer on a published specification I'll pick the manufacturer every time. You did have a link to the actual datasheet. Next time you'll know that high frequency opamps are not bloody likely.

 

[Nigel Goodwin]

I built the circuit shown in figure 3 of the data sheet. This circuit works great and gives me a pulse train out with frequency proportional to the light intensity. My output is between 40 and 80Hz depending on the amount of light I let hit the phototransistor. What I want to do is increase this output somehow to be in the 5+ Mega Hz range

Like I said before, tell us EXACTLY what you want to do, and WHY, you're still making no sense, and not giving enough information even if it did make sense.

 

[evandude]

Why in the world do you need it to be in the 5MHz range?

For starters, what I suggested earlier (a mixer) is probably not going to be useful since you clarified that you are talking about a digital pulse train... In case it wasn't made obvious enough already, you REALLY need to be more clear...

 

[Hero999]

PLL?

Convert it into a squarewave and then filter the harminics?

A single side band modulator?

All of the above will work but the one you want to use will depend on what you're doing.