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Tunable microstrip bandpass filter with constant absolute bandwidth using BST varactors and digitally tunable capacitors

Published online by Cambridge University Press:  08 March 2024

Manoj Kumar Open the ORCID record for Manoj Kumar [Opens in a new window]  and
Gowrish Basavarajappa Open the ORCID record for Gowrish Basavarajappa [Opens in a new window]
Manoj Kumar
Affiliation:
Electronics and Communication Engineering Department, Indian Institute of Technology Roorkee, Roorkee, India
Gowrish Basavarajappa*
Affiliation:
Electronics and Communication Engineering Department, Indian Institute of Technology Roorkee, Roorkee, India
*
Corresponding author: Gowrish Basavarajappa; Email: gowrish.biit@gmail.com; gowrish.b@ece.iitr.ac.in
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Abstract

In this paper, two second-order electronically tunable bandpass filters are presented. The filters are implemented in microstrip technology using barium–strontium–titanate (BST) varactors and digitally tunable capacitors (DTC) for tuning the frequency response of the bandpass filters. The filter realized using BST varactors has a 35% tuning range from 900 MHz to 1.275 GHz with an insertion loss variation from 3.1 to 2.6 dB. The absolute bandwidth is nearly constant over the entire tuning range, varying from 64 to 72 MHz (around ±5% variation). The filter realized using DTCs also has a 36% tuning range from 850 MHz to 1.225 GHz with an insertion loss variation from 3.1 to 1.5 dB. The absolute bandwidth is constant over the tuning range, varying from 88 to 98 MHz (around ±5% variation). The bandpass filters are tuned using a single control signal. The tunable bandpass filters are proposed for use in reconfigurable radios.

Keywords

BST varactorsconstant absolute bandwidthdigitally tunable capacitorsmicrostrip technologytunable band pass filter
Type
Research Paper
Information
International Journal of Microwave and Wireless Technologies , First View , pp. 1 - 7
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Copyright
© The Author(s), 2024. Published by Cambridge University Press in association with The European Microwave Association.

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