Electronic – Wideband Impedance Matching

impedance-matchingsmith chart

I have designed a common-emitter RF amplifier, with input and output impedance matched for my load and source impedance. I have used Smith Chart for the matching.

The matching is good for the designed frequency, but when using other frequencies the matching is poor (I get large reflections in my spice simulation).

I know that wideband matching (one that works for all frequencies) is not possible.

But if I want to make a fair matching in a frequency band, say 200 MHz to 600 MHz, is there any good technique for this?
(Except just trial and error with the Smith Chart).

Best Answer

That's a relatively wide bandwidth to match a circuit over. The Bode-Fano equation governs bandwidth/return loss for reactive circuits, and google has some articles that will help with this. As long as the impedances you are working with don't vary much, you can do a decent job of matching. Resistive matches are pretty broadband, but lossy.