NEW KIND OF INFINITE IMPULSE RESPONSE DIGITAL FILTERS INTENDED FOR PULSE PERIOD FILTERING

This paper describes a new kind of infinite impulse response (IIR) digital filter designed for pulse period filtering. The IIR digital filter is designed using a third -order IIR frequency locked loop (IIR FLL), which is based on the time measurement and processing of both, the input and output periods. A general form of the difference equation describing this type of IIR FLL of any order is developed and compared with the corresponding difference equation of classical digital filters. The mathematical analyses in time domain were performed using the Z transform approach and theory of linear discrete systems. An analysis of IIR digital filter was performed in time and frequency domain. The transfer functions and Z transform of the third -order IIR FLL outputs are developed. The main part of the article is devoted to design the appropriate IIR FLL digital filter using the corresponding IIR FLL. For this purpose, the theory of IIR digital filter and the corresponding MATLAB tools are used, but taking into account the differences of these systems. Filtering abilities of the designed IIR FLL digital filter are demonstrated. Computer simulation of the designed IIR FLL is made in the time domain to enable precise insight into its properties.