30. LC filter circuit
The filter has the function to pass through the signal of a specific bandwidth or to block. It is a basic filter circuit composed of LC (inductor and capacitor).
| Circuit example | Feature of the operation | |
|---|---|---|
|
LPF:Low Pass Filter |
|
The signal component of the high frequency cannot easily pass although the signal component of the low frequency area can pass because the impedance of L rises in the area where the frequency is high, simultaneously the impedance of C lowers. |
|
HPF:High Pass Filter |
|
The signal component of the low frequency cannot easily pass although the signal component of the high frequency area can pass because the impedance of L falls simultaneously as the impedance of C rises in the area where the frequency is low. |
|
BPF:Band Pass Filter |
|
The LC circuit connected in series can pass through only signal component of the resonance frequency vicinity. Further, the LC circuit connected in parallel becomes the resonance frequency vicinity, then it loses the function to let bypass the signal component to the ground. Therefore, it becomes possible to pass only the signal component of the band with the resonance frequency vicinity. |
