IIR second order Filter - Direct form2 (Sigma Studio)

Hi Joshua,

I moved your thread to the SigmaDSP Processors and SigmaStudio Development Tool community. Someone here will be able to assist you.

Best regards,

Mark

Hello sivaramakrishna,

They are all Direct Form 2. Here is the documentation that should be helpful for you.

General Filters [Analog Devices Wiki]

Thanks,

Dave T

No they're most definitely DF1. The wiki page you referred to also makes mention of DF1 but not DF2. The real question is why anyone would want DF2, since it is mathematically equivalent to DF1 but prone to internal clipping (since it buffers the intermediate result between the feedback and feedforward section in memory, whereas DF1 only keeps it transiently in an ALU register which has 16 extra bits of range exactly to prevent this internal clipping)

DF-1 and DF-2 filters are mathematically equivalent, the difference is merely an implementation detail, and DF-1 is almost always preferred in practice since it is less prone to internal clipping. The only benefit of DF-2, reduced buffer space, disappears when you have multiple filters back to back (which is very typical).