SLOA049D July   2000  – February 2023

1.   Abstract
2.   Trademarks
3. 1 Introduction
4. 2 Filter Characteristics
5. 3 Second-Order Low-Pass Filter Standard Form
6. 4 Math Review
7. 5 Examples
   1. 5.1 Second-Order Low-Pass Butterworth Filter
   2. 5.2 Second-Order Low-Pass Bessel Filter
   3. 5.3 Second-Order Low-Pass Chebyshev Filter with 3-dB Ripple
8. 6 Low-Pass Sallen-Key Architecture
9. 7 Low-Pass Multiple Feedback (MFB) Architecture
10. 8 Cascading Filter Stages
11. 9 Filter Tables
12. 10Example Circuit Simulated Results
13. 11Non-ideal Circuit Operation
    1. 11.1 Non-ideal Circuit Operation: Sallen-Key
    2. 11.2 Non-ideal Circuit Operation: MFB
14. 12Comments About Component Selection
15. 13Conclusion
16.   A Filter Design Specifications
    1.     A.1 Sallen-Key Design Simplifications
       1.      A.1.1 Sallen-Key Simplification 1: Set Filter Components as Ratios
       2.      A.1.2 Sallen-Key Simplification 2: Set Filter Components as Ratios and Gain = 1
       3.      A.1.3 Sallen-Key Simplification 3: Set Resistors as Ratios and Capacitors Equal
       4.      A.1.4 Sallen-Key Simplification 4: Set Filter Components Equal
    2.     A.2 MFB Design Simplifications
       1.      A.2.1 MFB Simplification 1: Set Filter Components as Ratios
       2.      A.2.2 MFB Simplification 2: Set Filter Components as Ratios and Gain = –1
17.   B Higher-Order Filters
    1.     B.1 Fifth-Order Low-Pass Butterworth Filter
    2.     B.2 Sixth-Order Low-Pass Bessel Filter
18.   C Revision History