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Scientific Calculator  
Sallen-Key Low-pass Filter Design Tool

This page is a web application that design a Sallen-Key low-pass filter. Use this utility to simulate the Transfer Function for filters at a given frequency, damping ratio ζ, Q or values of R and C. The response of the filter is displayed on graphs, showing Bode diagram, Nyquist diagram, Impulse response and Step response.
Filters
RC LPF
RC HPF
LR LPF
LR HPF
RLC LPF
RLC HPF
RLC BPF
RLC BEF
Sallen-Key LPF
Sallen-Key HPF
3rd order SallenKeyLPF
3rd order SallenKeyHPF
Multiple feedback LPF
Multiple feedback HPF
Multiple feedback BPF
3rd order Multiple feedback LPF
3rd order Multiple feedback HPF
TwinT notch
CR 2nd order LPF,HPF,BPF
Active filter


Filter index

Calculate the transfer function for Sallen-Key low-pass filter with R and C values
Vin(s)→ →Vout(s)
Transfer function:
R1=Ω C1=F
R2=Ω C2=F
p:pico, n:nano, u:micro, k:kilo, M:mega
Frequency analysis Bode diagram
Nyquist diagram(f=0→∞)
Pole, zero
Phase margin
Oscillation analysis
Transient analysis Step responseImpulse response
Overshoot
Final value of the step response


Calculate the R and C values for the Sallen-Key filter at a given frequency and Q factor
Vin(s)→ →Vout(s)
Cut-off frequency:
    
Transfer function:
    
fc=Hz
Q factor | Damping ratio ζ Quality factor Q =
Damping ratio ζ =
C1 = F C2 = F
C1, C2 is optional. But when setting these capacitances, C1 and C2 of both are needed to give following the equation
  (C2/C1) ≤ ζ 2
  (C1/C2) ≥ 4Q2

Select Capacitor Sequence:
Select Resistor Sequence:

Frequency analysis Bode diagram
Nyquist diagram(f=0→∞)
Pole, zero
Phase margin
Oscillation analysis
Transient analysis Step responseImpulse response
Overshoot
Final value of the step response


Calculate the transfer function for Sallen-Key low-pass filter with R and C values
Vin(s)→ →Vout(s)
Transfer function:
  Transfer function
R1=Ω C1=F
R2=Ω C2=F
R3=Ω
R4=Ω
p:pico, n:nano, u:micro, k:kilo, M:mega
Frequency analysis Bode diagram
Nyquist diagram(f=0→∞)
Pole, zero
Phase margin
Oscillation analysis
Transient analysis Step responseImpulse response
Overshoot
Final value of the step response


Calculate the R and C values for the Sallen-Key filter at a given frequency and Q factor
Vin(s)→ →Vout(s)
Cut-off frequency:
    
Transfer function:
    
fc=Hz
G= at f=0Hz (G>1)
Q factor | Damping ratio ζ Quality factor Q =
Damping ratio ζ =
C1 = F C2 = F
C1, C2 is optional. But when setting these capacitances, C1 and C2 of both are needed to give following the equation
  G-1 < C2/C1 ≤ ζ 2+G-1


Select Capacitor Sequence:
Select Resistor Sequence:

Frequency analysis Bode diagram
Nyquist diagram(f=0→∞)
Pole, zero
Phase margin
Oscillation analysis
Transient analysis Step responseImpulse response
Overshoot
Final value of the step response



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