Design of High Frequency Filters for RF Applications

Abstract

Filters are the significant Radio Frequency (RF) and Microwave component. It plays a vital role in RF/microwave applications especially in receiver system design. They are used to separate or combine different frequencies. Commonly lumped and distributed element filters are classified into Low pass filter (LPF), High pass filter (HPF), Band pass filter (BPF) and Band stop filter (BSF). The design and implementation of the lumped and distributed elements filter are proposed in this paper for RF applications. Low pass filter is a circuit which allows only the frequency below the cut off frequency. At the outset Low pass filter are designed using the lumped elements such as inductor and capacitor with the frequency range of 1-5GHz.The inductors and capacitors used are selected as 65.9nH, 58.5nH, 5nH and 42.7pF respectively. These specified lumped elements are not physically available. Distributed filters are the practical solution of RF filter design. Physical length and width of the inductors are 150mil and 100mil respectively. Similarly, physical length and width of the capacitors are 150mil and 50mil respectively. Numerical Analysis results with the estimation of Insertion loss as 0dB at 4GHz. High pass filter is a filter which passes only the frequency above the cut off frequency and attenuates the frequency below the cut off frequency. Here it was designed using the lumped elements with the frequency range of 1-5GHz. The value of the inductors and capacitors used are 65.9nH, 58.5nH, 5nH and 42.7pF, 60pF respectively. Corresponding physical dimension L:W of the inductors are 150mm and 100mm respectively. Similarly, physical length and width of the capacitors are 150mm and 50mm respectively. The insertion loss obtained for the High pass filter is 0dB at 2GHz. Band pass filter is a filter which passes only the desired band of frequency. As LPF and HPF, Band pass filter also designed using the lumped elements with the frequency range of 2.3-2.7 GHz. The inductors and capacitors value mentioned here is 102.618nH, 0.088nH and 0.0395pF, 45.892pF respectively. The insertion loss obtained for the band pass filter is 0dB at a bandwidth of 100 MHz finally, band stop filter are designed to eliminate the undesired band of frequencies. Here the band stop filter was designed using the same lumped elements such as inductor and capacitor with the frequency range of 1-10GHz. The value of the inductors and capacitors used are 12.214nH, 0.0769nH and 0.0819pF respectively. The insertion loss obtained for the band stop filter is 0dB at 300 MHz bandwidth. Novel Filter designs are identified and implemented for ideal RF and Microwave Applications.