2.45 GHz small signal amplifier using customised bandpass filter as impedance matching circuits
Mazumdar, Partha Sarathi (2024)
2024
Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2024-11-19
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202410189362
https://urn.fi/URN:NBN:fi:tuni-202410189362
Tiivistelmä
This thesis explores a novel approach to designing a 2.45 GHz small signal amplifier utilizing customized bandpass filters for impedance matching. The proposed design offers significant advantages over conventional amplifier-filter topologies, including reduced loss, improved matching, and a more compact footprint.
The design incorporates two cascaded bandpass filters strategically placed within the amplifier circuit. The first filter, located at the receiver input, provides initial filtering to mitigate out-of-band noise and interference, protecting the small signal amplifier from potential damage caused by strong unwanted signals. The second filter, positioned at the amplifier output, serves the dual purpose of refining the desired signal bandwidth and achieving optimal impedance matching with subsequent receiver stages. By using customized bandpass filters, the design allows for precise control over both the frequency response and impedance transformation within the circuit. This thesis presents detailed simulation and measurement results for the amplifier-filter design, focusing on reflection loss and gain. The simulations predicted a reflection coefficient below -10 dB and a gain of 13.6 dB within the desired frequency range. While the measured results showed a reflection coefficient of -15.9 dB and a marginally lower gain of 11.3 dB, the overall performance was still within acceptable limits for the intended application. These discrepancies can be attributed to component tolerances and external influences during testing.
Future work could focus on further optimizing the design to reduce loss and improve overall efficiency by exploring different filter topologies, optimizing component values, or implementing advanced design techniques. Investigating alternative matching circuits using lumped elements or transmission line transformers could provide valuable insights for future iterations.
The design incorporates two cascaded bandpass filters strategically placed within the amplifier circuit. The first filter, located at the receiver input, provides initial filtering to mitigate out-of-band noise and interference, protecting the small signal amplifier from potential damage caused by strong unwanted signals. The second filter, positioned at the amplifier output, serves the dual purpose of refining the desired signal bandwidth and achieving optimal impedance matching with subsequent receiver stages. By using customized bandpass filters, the design allows for precise control over both the frequency response and impedance transformation within the circuit. This thesis presents detailed simulation and measurement results for the amplifier-filter design, focusing on reflection loss and gain. The simulations predicted a reflection coefficient below -10 dB and a gain of 13.6 dB within the desired frequency range. While the measured results showed a reflection coefficient of -15.9 dB and a marginally lower gain of 11.3 dB, the overall performance was still within acceptable limits for the intended application. These discrepancies can be attributed to component tolerances and external influences during testing.
Future work could focus on further optimizing the design to reduce loss and improve overall efficiency by exploring different filter topologies, optimizing component values, or implementing advanced design techniques. Investigating alternative matching circuits using lumped elements or transmission line transformers could provide valuable insights for future iterations.