IOSR Journal of VLSI and Signal Processing (IOSR-JVSP) e-ISSN: 2319 – 4200, p-ISSN No. : 2319 – 4197 Volume 1, Issue 6 (Mar. – Apr. 2013), PP 27-36 www.iosrjournals.org www.iosrjournals.org 27 | Page A High Performance & Efficiently Designed IIR Filter Using Graphical Virtual Tool (LabVIEW) Shikha Tiwari 1 , Rajinder Tiwari 1 , Amit Bajpai 2 1 Department of Electrical & Electronics Engineering, Amity University Uttar Pradesh, Lucknow 2 Department of Physics, Indian Institute of Technology, Kanpur Abstract: Designing of digital filters based on LABVIEW involves the concept of virtual instrumentation. In the recent years LABVIEW finds many applications in different fields for example industrial purpose like level sensor, temperature sensor pressure sensor etc. Virtual instruments are used in LABVIEW. Each VI has three parts a block diagram, a front panel and a connector panel. Connector panel is used to represent the VI in the block diagrams of other. Controls and indicators on the front panel allow an operator to input data into or extract data from a running virtual instrument. The front panel can also serve as a programmatic interface. A digital IIR filter system is developed using LABVIEW software. IIR filters possess certain properties which makes them preferred design choices in many situations over FIR filters. Following are the types of IIR filter Butterworth filters, Chebyshev filters, Inverse chebyshev filters, Elliptic filters. Virtual instrument reads the desired parameters of the filters entered by the user on the front panel and determines its magnitude response and filter coefficients. Keywords: ADC, DAC, DSP, Design Approach, Virtual instrument, LABVIEW, IIR filter. I. INTRODUCTION TO BASICS OF THE FILTERS The function of a filter is to remove unwanted parts of signal or to extract some useful parts of signal, such as the components lying within a certain frequency range. Fig.1 Block diagram of basic filter Infinite impulse response is a property of signal processing systems. IIR filters have impulse response function that is non zero over an infinite length of time. Simplest example of analog IIR filter is an RC filter made up of single resistor (R) feeding in to a node shared with single capacitor (C) . Impulse response of this filter is exponential characterized by RC time constant. The exponential function is asymptotic to a limit and thus never settles to a fixed value that’s why response is considered infinite. Digital filters use digital processor to perform numerical calculations on sampled values of signal. Block diagram of digital filter is given below. Fig.2 A block diagram of basic digital filter Firstly the input signal must be sampled and digitized using an analog to digital converter. The result of converter is binary numbers, representing successive sampled values of the input signal, which are transferred to the processor and it performs numerical calculation on them. These calculations involve multiplying the input values by constants and adding the products together.