3 Responses to “If frequency selective circuit can be built by using capacitors and resistors than why inductors are used?”

1. By JavaScript_Junkie on Apr 6, 2009 | Reply

   they do
   PLL
   References :

2. By dave on Apr 6, 2009 | Reply

   Because in an LC circuit, the L (inductor) has a cutoff frequency that allows lower frequencies to pass (low pass), while the C (capacitor) allows more to pass (high pass) as the frequency goes higher. Together they select a frequency to pass (band pass.) in an RC circuit it will pass more of the frequency as it gets higher, as it's only a high pass and can't be a frequency selector.
   References :

3. By billrussell42 on Apr 6, 2009 | Reply

   first, op amps don't work well at RF frequencies. Those that do are expensive.
   second, a frequency filter using only R's and C's has a pretty broad bandwidth, and would not select adjacent channels very well.
   References :