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Design and Implementation of a Low-Noise Microwave FET Mixer with High Conversion Gain to work in S-Band

Seraji, Parham | 2026

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58896 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Banai, Ali
  7. Abstract:
  8. The impact of the mixer element on the performance of a communication receiver is of great importance. This importance arises from the placement of this element in the first or second stage of an RF and microwave receiver. In such receivers, sensitivity and selectivity are directly influenced by the performance of this element. In many applications, the mixer is the first element following the input amplifier and makes a significant contribution to determining the overall noise figure of the receiver. Therefore, the design of a low-noise mixer is an essential requirement for a high-quality receiver. In order to design a low-noise mixer, it is first necessary to understand this nonlinear three-port element and to carry out nonlinear and noise analyses. In this thesis, the conversion matrix and noise correlation matrix methods are employed due to their high efficiency and computational speed in performing these analyses. Considering the significant role of impedance termination of frequency components, particularly the image frequency, in mixer operation, analytical expressions for gain and minimum noise figure are derived for single-diode and single-transistor active and passive FET mixers. Furthermore, the effect of impedance termination of these components on mixer characteristics is investigated. In addition, a set of design rules for this class of mixers is presented. Finally, to validate the findings, an active single-transistor FET mixer pumped from the gate terminal in the S-band is designed, implemented, and experimentally characterized. The implemented mixer belongs to the class of image-enhanced mixers. Measurement results indicate that the noise figure of the implemented mixer is comparable to that of existing mixers and is approximately 1.45 dB, with a conversion gain of 12.24 dB
  9. Keywords:
  10. Mixer ; Noise Figure ; Conversion Matrix ; Noise Analysis ; Single-Ended Transistor Mixer ; Single-Ended Diode Mixer ; Conversion Gain

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