Linear-Phase FIR Transfer Functions It is nearly impossible to design linear- phase IIR transfer function It is always possible to design an FIR transfer function with an exact linear-phase response
Stability Condition in Terms of the Pole Locations A causal lti digital filter is BIBO stable if and only if its impulse response h[n] is absolutely summable, i.e
Phase and Group Delays The output y[n] of a frequency-selective LTI discrete-time system with a frequency response(@) exhibits some delay relative to the input x[n] caused by the nonzero phase response 0(@) =arg{()} of the system
