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A Fully Differential Highly Linear Low Power Ultra Wideband LNA

Ghasemi, Reza | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 47331 (55)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Haj Sadeghi, Khosro
  7. Abstract:
  8. This work uses a hierarchical approach for designing the integrated UWB LNA in MOSFET technology. It first offers a brief treatment of the two important types of noise: the thermal noise of channel and the gate-induced noise, in MOSFET. Then the CS and CS-CG configurations for narrow-band LNAs are considered and the requirements for the wide-band operation in UWB are specified. Noise cancelling technique is also introduced, while five wideband prototype designs, with the noise-cancelling technique used in two designs, are re-examined and tested by simulation. Some proposed methods are then applied to these designs for better performance and obtaining practical insight. The final main contribution of the thesis is achieved where a prototype narrowband differential design is modified and converted into two LNAs for UWB application in the 7.5 GHz bandwidth of interest. Then these circuits are further modified and simulated. The minimum power gain of both architectures in the -3 dB bandwidth is quite higher than 10 dB. The first design attains 3.35 dB as its maximum noise figure, which is a very good value for a UWB differential LNA. A novel local feedback is created for the first time and applied to the second design. The proposed design relaxes the constraint of implementing a feedback path connected at one end to one branch of the cross-coupling rout, and provides the input matching enhancement for the lower portion of the desired bandwidth. This design achieves an even lower value of 2.84 dB as the maximum noise figure. Moreover, both the designs enjoy high linearity so that the maximum IIP3 for each one is higher than 11 dBm at 6.5 GHz, which is about 10 dBm better than the majority of the typical IIP3 values reported in published works
  9. Keywords:
  10. Feedback ; Linearization ; Cross Coupling the Resonators ; Inductive Source Degenerated ; Low Noise Amplifier (LNA) ; Ultra Wideband ; Noise Figure ; Noise Removing

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