Amplifier 13.56MHz

What I am doing is a preamp and the load of this preamp is an RF amp with an input impedance of 50ohm. If I want max power transfer, I guess I need an IC with Rout = 50 ohm. Or is there something I don't understand...

You are totally right. My bad. Maybe I should try your idea of discret design. Is there a note of Analog Device and maybe a transistor number you can give me to help my start my project?

thanks.

Albertin,

  If you have an RF signal chain, and you want maximum power transfer, you match impedances.

What you really want, is zero ohm output impedance so you get the maximum voltage into your

load.

Harry

Albertin,

  Your RF amp doesn't know what is driving it.  You want the maximum voltage swing across it's input

impedance to get the best SNR.  If the op amp had Rout of 50 ohms, you would loose half the signal.

You want a perfect voltage source driving your RF amp; i.e., zero ohm output impedance.

As a side note, I would not use an op amp for a preamp.  A one or two transistor discrete design

is much better.

Harry

Albertin,

  We don't make any transistors, so don't have app notes, but check the freescale website and the siliconix

website.  Also google "RF amplifier design"

Harry

You must try discrete transistor design which can be searched from ARRL hand book or QSL, QEX web sites.

The frequency nearly matches 20m amplifier design.