IIR First Order Low Pass Filter

Description

SPICE simulation of IIR filter. A filter with feedback from the output is called a recursive infinite impulse filter IIR. A recursive filter is one where the present output depends on past output values. Here there are two terms: the original input signal x(n), and a delayed output signal y(n – 1) multiplied by the filter coefficient b, so that: y(n) = x(n) + b0 y(n – 1). This circuit simulates the AC response of a first order low pass filter. The cutt off frequency is: fc = fs/(2* 3.14) * cos-1 {(4*b0 – 1 – bo^2)/2*b0}. For b0 = 0.9 and fs = 8000 the cutt off frequency (-3dB) is 134Hz.

• Project Type: Free
• Complexity: Simple
• Components number: <10
• SPICE software: PSpice
• Software version: 9.1+
• Full software version nedeed : No
• Screenshots simulation images: