# Q and gain in tank circuit

1. Dec 29, 2008

### Idea04

I would like to know somethings about the Q and its relation to gain in a parallel LC circuit.
From what I know by tuning the Q to be high you can get alot of gain at resonant frequency. Also to tune for Q the inductance has to be decreased and the capacitance has to be increased. Is this right? If so then for a matter of speaking, if you had a capacitance of 10000 microF and 1 microH for a resonant frequency would there be more gain than 1000 microF and 1000 microH for a resonant frequency. I think that the lower the impedance in the circuit the higher the gain will be. can someone clarify this.

2. Dec 29, 2008

### Phrak

You may want to go to Wikipedia and look up "Q factor" and "RLC circuit".

To increase the Q factor you minumize the losses due to resistance. You don't always want to maximize the Q. The bandwidth decreases with increased Q. It all depends on what you want to amplify.

For an LC circuit with resistance (RLC) wikipedia gives the Q as:

$$Q=\frac{1}{R}\sqrt{\frac{L}{C}}$$