Editing Sallen–Key topology (section)

==Explanation of operation==
A VCVS filter uses a voltage amplifier with practically infinite [[input impedance]] and zero [[output impedance]] to implement a [[Pole (complex analysis)|2-pole]] [[low-pass]], [[high-pass]], [[bandpass]], [[band-stop filter|bandstop]], or [[allpass]] [[frequency response|response]]. The VCVS filter allows high [[Q factor]] and [[passband]] gain without the use of [[inductor]]s. A VCVS filter also has the advantage of independence: VCVS filters can be cascaded without the stages affecting each others tuning. A Sallen–Key filter is a variation on a VCVS filter that uses a [[unity gain]] amplifier (i.e., a [[buffer amplifier]]).