5.4.3 Types offilters · RC lower- pass filter de Rc-o+e =e dt (5.63) H +1 (5.64) where the frequency f=_1 2TRO corresponds to the point of amplitude attenuation of -3dB, and is the upper cut-off frequency.5.4.3 Types of filters • RC lower-pass filter o i o e e dt de RC + = ( ) 1 1 ( ) + = = s s e e H s i o  (5.63) (5.64) where the frequency RC f 2 1 = corresponds to the point of amplitude attenuation of –3dB, and is the upper cut-off frequency