OKAWA Electric Design
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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.

Sample calculation

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
    Phase  Group delay
Nyquist diagram
Pole, zero
Phase margin
Oscillation analysis

Upper and lower frequency limits:
  f1= - f2=[Hz] (frequency limits are optional)

Transient analysis

Step response
Impulse response
Overshoot
Final value of the step response

Simulation time:
  0 - [sec] (optional)


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
    Phase  Group delay
Nyquist diagram
Pole, zero
Phase margin
Oscillation analysis

Upper and lower frequency limits:
  f1= - f2=[Hz] (frequency limits are optional)

Transient analysis

Step response
Impulse response
Overshoot
Final value of the step response

Simulation time:
  0 - [sec] (optional)


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
    Phase  Group delay
Nyquist diagram
Pole, zero
Phase margin
Oscillation analysis

Upper and lower frequency limits:
  f1= - f2=[Hz] (frequency limits are optional)

Transient analysis

Step response
Impulse response
Overshoot
Final value of the step response

Simulation time:
  0 - [sec] (optional)


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
    Phase  Group delay
Nyquist diagram
Pole, zero
Phase margin
Oscillation analysis

Upper and lower frequency limits:
  f1= - f2=[Hz] (frequency limits are optional)

Transient analysis

Step response
Impulse response
Overshoot
Final value of the step response

Simulation time:
  0 - [sec] (optional)


Filter tools

  1. RC LPF
  2. RC HPF
  3. LR LPF
  4. LR HPF
  5. RLC LPF
  6. RLC HPF
  7. RLC BPF
  8. RLC BEF
  9. Sallen-Key LPF
  10. Sallen-Key HPF
  11. 3rd order SallenKeyLPF
  12. 3rd order SallenKeyHPF
  13. Multiple feedback LPF
  14. Multiple feedback HPF
  15. Multiple feedback BPF
  16. 3rd order Multiple feedback LPF
  17. 3rd order Multiple feedback HPF
  18. TwinT notch
  19. CR 2nd order LPF,HPF,BPF
  20. Active filter

Filter index