PURPOSE
Design an active second order Low-pass filter and characterize its frequency response.EQUIPMENT AND COMPONENTS Oscilloscope Power Supply Function Generator UA741 or LM741 OP AMP 4.7 nF Capacitors
Resistors
PRELAB 1. The RC circuit is shown in the following figure. Node Voltage Analysis is done in order to generate a transfer function Tvs=V2sV1s. In the circuit, voltage at node A is also the input voltage (V1=VA), and voltage at node D is also the output voltage (V2=VD).
KCL at node B:
V1-VBR1=VB-V21/sC1+VB-VCR2 (1)
KCL at node C:
VB-VCR2=VC1/sC2 (2) V2=uVC→VC=V2u (3)
Simplifying (2):
VB=VC1+sR2C2 (4)
Then, substituting (3) to (4):
VB=V2u1+sR2C2 (5)
Substituting (3) and (5) to (1):
V1-V2u1+sR2C2R1=V2u1+sR2C2-V21sC1+V2u1+sR2C2-V2uR2 V1-V2u1+sR2C2R1=V2u1-u+sR2C21sC1+V2usR2C2R2 V1-V2u1+ ...