Hi,
One of the key points hinted at by Ratch is that the inductor should be relatively large. The larger the inductance, the better the circuit works with a given resistance which eats up energy. It's a little hard to do in practice because you have to find an inductor that has enough inductance to cause a voltage boost, yet that very same inductor has to have low series resistance. Of course at 20kHz that might be much easier than at say 60Hz line frequency.
For example a 500uH inductor would probably work pretty nice at boosting the voltage at 20kHz with the appropriate capacitor value (around 0.127uf).
You have to be a little careful though, to watch the sensitivity of the circuit with respect to the component values. If the chosen LC pair create too sharp of a response, just like a filter it will not work as well if one or both of the components changes value by some percentage. This means you probably should not design it to have too sharp of a response. 500uH and 0.127uf might be too sharp so you may have to come down on the inductor value.
Lowering the inductance by a factor of 0.5 and increasing the capacitor value by a factor of 2 keeps the same center frequency, but lowers the boost by about 0.5 too, but also reduces the sensitivity to component variation.