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Design and Development of Low Noise Active Inductors and a Novel General Theory for Low Phase Noise Oscillators in RF Receivers

Moezzi, Mohsen | 2013

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 44936 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Sharif Bakhtiar, Mehrdad
  7. Abstract:
  8. In this thesis, we intend to explore the application of active inductors in high-performance radio receivers. The proposed active inductor uses a feed-forward path to improve the noise performance. This is done without sacrificing the quality factor and the power consumption. The proposed active inductor is designed and implemented in a standard 0.18μm CMOS technology. The measurement results show an almost three fold improvement in the noise performance, comparing to the typical existing structures. The resonance frequency of the inductor can be tuned from 1.8 GHz to 5.5 GHz, while the quality factor can be adjusted up to 30. The total current consumption of the active inductor is 4.8 mA.
    The proposed active inductor is then employed to implement the input matching network of a fully on-chip low-noise amplifier (LNA). This provides a tunable input matching over a wide frequency range. It is shown that this tunability can also be used to provide a wideband trade-off between the noise performance and the power consumption. The LNA employs an additional feed-forward path to cancel a significant portion of the noise generated by the active inductor. As a result, a low noise figure is achieved with low power consumption. The LNA is designed in 0.18μm CMOS technology, for the frequency range between 0.32 GHz and 1 GHz. The measurements show a noise figure ranging from 2.2 dB to 2.7 dB, a voltage gain of higher than 18 dB, and a return loss of better than 10 dB. Occupying less than 0.1mm2 of die area, the LNA chip consumes a total dc current of 8.5 mA.
    The possibility to utilize active inductors in low phase-noise oscillators is also investigated. For this purpose, a new perspective is introduced for the study of the phase noise and its relation to the resonator network. As a result, a generalized model for the phase noise of oscillators is presented. Based on this model, the parameter of the inductance energy factor (IEF) is introduced. Disregarded in the existing phase noise models, IEF explains that, apart from the trivial methods of increasing the quality factor, the phase noise can also be improved by modifying the voltage transfer function of the inductors. Using the IEF concept, a method for improving the resonator networks is also proposed, which results in more than 10 dB reduction in the phase noise. To verify the viability of the method, a 2.4 GHz oscillator is designed. In order to stabilize the oscillation, additional poles and zeros are introduced in the oscillation loop’s transfer function using an active inductor. Simulation results show a significant improvement in the phase noise.
  9. Keywords:
  10. Active Inductor ; Phase Noise ; Gyrator ; Low Noise Amplifier (LNA) ; On-Chip Matching Network ; Noise Figure ; Tunability ; Resonator ; Phase Oscillator

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