Problems implementing IIR filter in VHDL

1. What are the disadvantages of IIR filter?
2. Why are IIR filters not stable?
3. How are IIR filters implemented?
4. Why IIR digital filters Cannot have linear phase?

What are the disadvantages of IIR filter?

The disadvantage of IIR filters is the nonlinear phase response. IIR filters are well suited for applications that require no phase information, for example, for monitoring the signal amplitudes. FIR filters are better suited for applications that require a linear phase response.

Why are IIR filters not stable?

(a) Stable IIR filter, (b) The same IIR filter becomes unstable due to rounding effects. , one poles lie exactly on the unit circle (ie, it is just out of the region of stability) and hence it is an unstable IIR filter.

How are IIR filters implemented?

Use a function to implement each biquad, such as the example C biquad function or a biquad function supplied with a DSP library. Export biquad coefficients from your IIR design program in the format required by the biquad function you use. Implement the overall IIR filter by cascading biquads.

Why IIR digital filters Cannot have linear phase?

For an IIR filter to satisfy the linear phase condition, both the poles and zeros would need to have mirror images outside the unit circle of the z-plane. However, poles outside the unit circle ⇒ unstable. Therefore, a causal, stable IIR cannot have linear phase.