The past outputs terms y(n–k) will be absent for a FIR filter because a FIR filter does not have feedback. Therefore, from Eq. (12.26) we can write that
Taking z-transform of Eq. (12.26) we get
Eq. (12.29) gives the transfer function of FIR system. The inverse z–transform of the above equation gives
Eq. (12.30) gives the unit sample response of FIR system.