[dragontamer]

Which one?

MCP6002 jellybean is GBP of 1MHz. Most "jellybean" OpAmps I know cap out at 10MHz GBWP (aka: a useless 10x gain at 1 MHz).

LM358B is 1.2 MHz GBWP or even 700kHz depending on the design. Magnitudes away from 20MHz especially when you want more than 1.0x gain.

If you want even 10x gain (aka around 10% error), you might suffice with 200MHz GBWP at 20MHz. Or maybe get a nice ADC and just go all digital given today's equipment...

Come on man. Typical "high speed" OpAmps are like 100MHz GBWP or less... correlating to only 5x gain at 20MHz. This sort of stuff is well outside "jellybean" amps. And I'm not even sure if a 100MHz amp is very effective at 20MHz.

[ErroneousBosh]

LT1812 is my weapon of choice for ultra low RF stuff (think Tayloe mixer frontends). Readily available, pennies to buy, reasonably flat to about 20MHz although THD is getting a little rough up there, possibly because I'm using it wrong.

They cost pennies.

[dragontamer]

https://www.digikey.com/en/products/detail/analog-devices-in...

Looks like they're closer to $3+? Like this is more expensive than a lot of microcontrollers for just one OpAmp.

I wouldn't call any Analog Devices / Linear Technologies parts to be a jellybean. Jellybean means matching common specs that any manufacturer can do.

But at $3 per chip, that's very far away from jellybean status. And AD / LT devices are known for high quality that no one else replicates.

> although THD is getting a little rough up there

Yeah, because a 100MHz high speed OpAmps only has 5x gain at 20MHz. So your error is now well in excess of like 20% (best case) or probably way way worse errors in practice.

As I said earlier: Im not even convinced that 100MHz OpAmps have the GBWP to effectively operate on 20MHz signals. You need more GBWP than that to be comfortable.