Implementing IIR Digital Filters

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1997 Microchip Technology 1 INTRODUCTION This application note describes the implementation ofvarious Digital Filters using the PIC17C42, the firstmember of Microchip s 2nd generation of 8-bitmicrocontrollers. The PIC17C42 is a very high speed8-bit microcontroller with an instruction cycle time of250 ns (@ 16 MHz input clock). Even though thePIC17C42 is an 8-bit device, it s high speed and effi-cient instruction set allows implementation of Digital fil-ters for practical applications. Traditionally Digital filtershave been implemented using expensive Digital SignalProcessors (DSPs).

AN540 DS00540C-page 2 1997 Microchip Technology Inc. Realization of the above equation is called the Direct Form II structure. For example, in case of a second