Design and Practical Implementation of 2.45 GHz Ultra-Low Noise RF Amplifier
Dhar, Mithun (2024)
2024
Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2024-11-11
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202410159283
https://urn.fi/URN:NBN:fi:tuni-202410159283
Tiivistelmä
In today’s era of global wireless communication, it is crucial for a system to receive and amplify weak radio frequency (RF) signals, traveling across vast distances, without distortion. The noise figure of an RF system, a measure of added noise, determines the clarity and reliability of these communications. Low-noise amplifier (LNA), the first active component in a receiver chain, plays a key role in amplifying signal strength while minimizing the added noise. The advancement of LNA represents a significant milestone in RF technology, similar to how the transistor revolutionized electronics. This thesis focuses on designing, optimizing, and implementing an LNA for applications operating at 2.45 GHz frequency, achieving a low noise figure and sufficient gain as the primary objectives.
The design of the LNA utilized the GRF2072 transistor, which offers a high gain and low noise figure with an active bias control system. The design and simulation process was carried out using Advanced Design System (ADS) software. Unconditional stability was ensured by designing stability networks with resistive loads. Moreover, the input impedance was matched to the transistor’s optimum reflection coefficient (Γopt), using the Smith chart tool in ADS, to obtain the minimum noise figure. The output matching network was designed with capacitors and microstrip lines for optimal power transfer. Lumped components were used limitedly, except for essential DC blocks and RF chokes, for a minimized noise figure. Parasitic elements were introduced to the components for reflecting real-world behavior and microstrip lines were optimized for desired performance. Subsequently, a layout was generated in ADS once the design goals were matched in the simulation.
The layout was implemented on a custom-manufactured PCB using the LPKF Protomat S104 milling machine with key components assembled through manual and hot air gun soldering techniques. The gain and other S-parameters of the prototype were measured using a VNA. Furthermore, the noise figure was measured utilizing the Y-factor method while an isolation cabinet was employed for interference-free measurement. The measured results from the prototype demonstrated a gain of 12.4 dB and a noise figure of 1.3 dB, meeting the target specifications for practical low-noise applications. The LNA prototype exhibits unconditionally stable performance across the entire frequency range and an OIP3 of 14.4 dBm, indicating good linearity.
This work contributes to the field by enhancing the performance of LNA, particularly in terms of lower noise figures and improved linearity. These advancements make it suitable for high-performance RF systems, ensuring better signal quality and minimizing distortion in communication applications.
The design of the LNA utilized the GRF2072 transistor, which offers a high gain and low noise figure with an active bias control system. The design and simulation process was carried out using Advanced Design System (ADS) software. Unconditional stability was ensured by designing stability networks with resistive loads. Moreover, the input impedance was matched to the transistor’s optimum reflection coefficient (Γopt), using the Smith chart tool in ADS, to obtain the minimum noise figure. The output matching network was designed with capacitors and microstrip lines for optimal power transfer. Lumped components were used limitedly, except for essential DC blocks and RF chokes, for a minimized noise figure. Parasitic elements were introduced to the components for reflecting real-world behavior and microstrip lines were optimized for desired performance. Subsequently, a layout was generated in ADS once the design goals were matched in the simulation.
The layout was implemented on a custom-manufactured PCB using the LPKF Protomat S104 milling machine with key components assembled through manual and hot air gun soldering techniques. The gain and other S-parameters of the prototype were measured using a VNA. Furthermore, the noise figure was measured utilizing the Y-factor method while an isolation cabinet was employed for interference-free measurement. The measured results from the prototype demonstrated a gain of 12.4 dB and a noise figure of 1.3 dB, meeting the target specifications for practical low-noise applications. The LNA prototype exhibits unconditionally stable performance across the entire frequency range and an OIP3 of 14.4 dBm, indicating good linearity.
This work contributes to the field by enhancing the performance of LNA, particularly in terms of lower noise figures and improved linearity. These advancements make it suitable for high-performance RF systems, ensuring better signal quality and minimizing distortion in communication applications.