Chien-Jung Li

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Elucidating how local oscillator (LO) pulling affects a wireless direct-conversion transmitter that uses constant envelope modulation is of concern for global system for mobile communication (GSM). Therefore, this paper presents a phase dynamic model for a phase-locked loop (PLL) under directly modulated self-injection to evaluate the degraded phase noise(More)
A novel vital-sign sensor with a self-injection-locked oscillator and a frequency demodulator to reduce system complexity and improve sensitivity is proposed. The theory provides a delta-sigma model to account for the excellent signal-to-noise spectral density ratio in a parametric study of the sensitivity performance. Then, the experiments verify the(More)
A novel RF sensing circuit for a cognitive radio to sense spectral environment is proposed using injection locking and frequency demodulation techniques. The research starts with deriving a generalized locking equation for oscillators as a theoretical basis, and then develops the sensing principle and circuit architecture to a practical and useful level. To(More)
This paper presents design and linearization techniques for a highly efficient, but nonlinear Class-E power amplifier (PA) applied to linear RF transmitters. To achieve maximum efficiency for Class-E PA operating above gigahertz frequencies, the proposed design theory modifies the classic Class-E condition and considers switch-on and switch-off resistances(More)
The envelope elimination and restoration (EER) approach developed by Kahn and its modern derivative, a polar transmitter, are well recognized as highly efficient amplification schemes. This paper presents an EER/polar dual-mode transmitter using injection-locked oscillators (ILOs). For an EER operation, an ILO that is combined with a mixer and a low-pass(More)
This study presents injection-pulling effects on a local oscillator (LO) for wireless applications. A discrete-time analysis is provided to predict output spectra of the LO pulled by a sinusoidal and angle-modulated injection signal. A phase-locked loop synthesizer with an injection signal is analyzed in frequency domain to account for the inherent bandpass(More)
A novel cognitive polar receiver that utilizes two injection-locked oscillator stages to extract the modulation envelope and phase components of a received nonconstant envelope modulation signal without using phase-locked-loop-based carrier recovery circuitry is presented. The paper begins with a theoretical analysis of injection locking and pulling(More)
A phase- and self-injection-locked radar is presented for robust vital-sign detection. The dc offset from the clutter is eliminated by using a dual-tuning voltage-controlled oscillator without complex clutter cancellation techniques. Phase noise analysis shows that the proposed radar has the advantages of both phase-locked oscillators and(More)
This study presents injection pulling effects on a local oscillator (LO) for wireless applications. A phase-locked loop under injection is analyzed in frequency domain to account for the inherent band-pass filtering on an injection signal. A discrete-time analysis is also provided to predict output spectra of the LO pulled by a sinusoidal and modulated(More)
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