A new implementation algorithm of second-order IIR digital filters

In the implementation of a second-order IIR digital filter, five multiplications and four additions are required for each output sample calculation. In this correspondence we present a new implementation algorithm which requires four multiplications and seven additions per output sample, and the output sequence can be produced at uniform rate without introducing any artificial delay in the filter. Since the number of operations (such as multiplication, addition, data transfer, etc.) between any two consecutive input samples are kept the same, the design of the control section is quite simple. For the circumstances where multiplication time dictates the filter speed, the new algorithm achieves 20 percent improvement on the filter speed.