CONCEPTUAL TOOLS	By:  Neil E. Cotter	Filters
		RC and RL low-pass filters
		Gallery

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Tool:        The RC and RL circuits shown below act as one-pole low-pass filters.

RC cutoff frequency:  RL cutoff frequency: 

Fig. 1.  Series LC band-pass filter.                      Fig. 2.  Parallel LC band-pass filter.

Tool:        The RLC circuits shown below act as two-pole band-reject filters.

Series or parallel LC:   (resonant frequency; zL = -zC)

  (lower cutoff frequency)

  (higher cutoff frequency)

Series LC:                                            Parallel LC: 

Fig. 1.  Series LC band-reject filter.                    Fig. 2.  Parallel LC band-reject filter.