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Amplifying MHz signals

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Infraviolet:
I need to amplify some 3MHz sine wave signals by a factor of around 5, with an amplification method which keeps signal magnitudes proportional (so a 0.1V peak to peak would come out as 0.5Vpp, a 0.3Vpp to 1.5V and so on).

The trouble is the rail to rail op-amps I've got to hand (MCP6024 and MCP6294, GBWP 10MHz) can't keep up with it, their maximum slew rate is around 6V/us, and the signal varies about this fast even when unamplified.

I'm in a situation where I've only got 5V and ground power rails, no negative rails or higher voltages available.

I can drive a few mA of current from the unamplified signal if necessary, so a method for amplifying does not need supr high impedance inputs.

The key things I need to preserve in the amplified signal are the peak voltage of the sine wave (accurately), and whether it is in phase or in anti-phase with another similar sine signal. I would be ok with getting something as distorted as a square wave out so long as peak voltage and phase were preserved.

My assumption is at these frequencies one starts using methods more similar to those for RF amplification rather tha using op amps, unfortunately I know very little about RF, so any suggestions of circuit types to search for would be helpful.

Can anyone suggest how I might do this?
Thank you

TimFox:
You can use coupling capacitors at MHz frequencies, and keep the DC level midway between your rails.
Fast op amps are ubiquitous.

Vovk_Z:
You may try low-voltage fast (almost jelly-bean except price) opamp AD8066.

RJSV:
To create a virtual ground you simply make a divider between your zero and +5 volts, that could be a 10 k resistor up, to +5, and another 10 k down, to zero.  Put a fairly large cap, like 5 ufd or larger, and you have an ac reference point.
To obtain more details perhaps try to search on some similar analog application notes, for another type of IC, like maybe LM358.
I've used circuits with the (quad pack) LM324, although that one can't deliver output all the way up to your + rail...    Still lots of info in various application notes...maybe too much at first.

tszaboo:

--- Quote from: Infraviolet on June 05, 2023, 01:41:52 am ---My assumption is at these frequencies one starts using methods more similar to those for RF amplification rather tha using op amps, unfortunately I know very little about RF, so any suggestions of circuit types to search for would be helpful.

Can anyone suggest how I might do this?
Thank you

--- End quote ---
Nah, you don't need RF stuff for that, regular, but fast opamp will do. Read the datasheet, there is someting called GBW, gain bandwidth, you need minimum of 15 MHz of that, since you have a 3MHz signal and your gain is 5. And then you calculated the slew rate, which is ballpark 1.42 x f x u = 21V/us. I would try the OPA2350, which would be my goto opamp for such a task, but there are a few that you can try. You also want all the resistors in the 1 KOhm range and not significantly higher so your stray capacitances are not turning it into a filter (or oscillator).