Page 93 - DSP Integrated Circuits
P. 93
78 Chapter 3 Digital Signal Processing
Figure 3.15 Group delay for the third-order digital lowpass filter
It should be noted that transmission zeros on the unit circle do not affect the group
delay, and that the group delay is proportional to the sample period. Hence, we
have
The group delay can therefore be reduced by increasing the sampling fre-
quency, but the system has to be adjusted accordingly.
3.11 TRANSFER FUNCTION
A behavioral description of an LSI system is the transfer function, which can be
obtained by applying the z-transform to both sides of Equation (3.11). We get
