# Is this current phase shifter ?

1. Jul 28, 2012

### JJ91

I'm not very familiar with all electronics (power engineering student) but this circuit especially qoes on my head for couple of days now:

Haven't seen such topology but would this circuit change the phase of the supply current with respect to the output point ?

My task is to find a transfer function for this circuit thus I would like to get to know what is the exactly the name of this circuit and its task in electronic world ;)

Thanks,
Tom

2. Jul 28, 2012

### vk6kro

That is a series tuned circuit.

At a resonant frequency, the reactances of the inductor and capacitor are equal and opposite and they cancel each other out, leaving only the resistance of the resistor to limit the current in this circuit.

At that frequency, the voltage across C (and L) reaches a maximum and may be a lot larger than the input signal.

They are not usually used to shift phase, but they can be used to choose one frequency when there are several frequencies present, because of the effect described in the last paragraph.

They will work at any frequency, but they are typically used in the frequency range 100 KHz to 30 MHz.

3. Jul 28, 2012

### dlgoff

And the value of the resistor determines how frequency selective the circuit is.

The measure of a circuits selectivity is the Q of a Circuit (quality factor).