el00
Member level 5
Hello I have a sallen-key topology lowpass, as in picture, which cuts at 40kHz.
Now, this is an antialiasing filter after a DAC and before a power amplifier. I need to add a stronger filter, and the only way I have is to insert a filter after the existing one and before the poweramp.
How can I calculate the new filter? Suppose I need a 2 or 4 additional poles, how do I take in account that there is already an the existing one in place? Usually all the tools do not allow modifying existing topology, and I know that cascading filters can be a complex task.
Now, this is an antialiasing filter after a DAC and before a power amplifier. I need to add a stronger filter, and the only way I have is to insert a filter after the existing one and before the poweramp.
How can I calculate the new filter? Suppose I need a 2 or 4 additional poles, how do I take in account that there is already an the existing one in place? Usually all the tools do not allow modifying existing topology, and I know that cascading filters can be a complex task.