Active Low-Pass Filter Design

Active Low-Pass Filter DesignApplication Report
SLOA049B - September 2002

Active Low-Pass Filter Design
Jim Karki ABSTRACT This report focuses on active low-pass filter design using operational amplifiers. Low-pass filters are commonly used to implement antialias filters in data-acquisition systems. Design of second-order filters is the main topic of consideration. Filter tables are developed to simplify circuit design based on the idea of cascading lowerorder stages to realize higher-order filters. The tables contain scaling factors for the corner frequency and the required Q of each of the stages for the particular filter being designed. This enables the designer to go straight to the calculations of the circuit-component values required. To illustrate an actual circuit implementation, six circuits, separated into