Picking source resistance for impedance matching

Question

I am trying to drive a piezoelectric transducer with maximum power transfer possible with minimum possible noise. In order to do that I am trying to implement LC matching circuit such as circuit described in below picture.

Websites that calculates L and C values for me ask for source and load impedance. Load impedance is fixed by the characteristics of piezoelectric transducer. However, I have the liberty of choosing the value of source impedance as it is from a gate driver with output impedance smaller than 10 Ohms. I can add just a series resistor to create my source impedance.

My question is that, is there any guidelines for choosing the value of source resistance? I noticed that as I make it smaller and smaller, the power transfer at resonant frequency increases along with Q value.

Answer 1

My question is that, is there any guidelines for choosing the value of source resistance?

Given that you want to send X watts to the transducer and that your driver has an amplitude of Y, source resistance is chosen to be what it has to be to both prevent the transducer from becoming damaged (read its data sheet) and/or to protect the driving source from damage due to excessive currents.

It's called "the design process".

Answer 2

This is a classic electronics 101 question. Instead of writing an answer here I'll point you to a more detailed explanation of the goal. Reduce the load and the matching network into the load the source sees, and you can find the answer.