Impact of Total-Ionizing Dose on Injection-Locked Voltage-Controlled Oscillators
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Sam, Delwyn G.
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Abstract
Voltage-controlled oscillators (VCOs) are key components in providing periodic signals that are used in RF communications systems for time synchronization and signal processing. However, standalone VCOs can have poor phase noise performance and experience frequency drift; therefore, injection locking can be implemented in a VCO to stabilize these performance metrics. Injection-locked VCOs (ILVCOs) in satellite communications or radar systems can be subject to total- ionizing dose (TID) effects, which could alter the performance of the oscillator. The present work analyzes the effects of TID in a 5 GHz ILVCO using an X-ray source, and demonstrates that the locking range increases and phase noise of the ILVCO improves with total dose. This unexpected result was analyzed using circuit simulations and shows that the threshold voltage shifts induced by TID raises the ratio of injection signal current to oscillator signal current, which equates to extending the locking range. Consequently, the increase in locking range may also lead to the decrease of phase noise. These improvements suggest that use of ILVCOs in satellite systems may provide performance benefits and is TID radiation tolerant compared to standalone oscillators.
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2024-12-11
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Text
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Thesis (Masters Degree)