Salvatore Levantino

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—A new concept for quadrature coupling of oscil-lators is introduced and demonstrated on a 5-GHz CMOS voltage-controlled oscillator (VCO). It uses the second harmonic of the outputs to couple the oscillators. The technique provides quadrature over a wide tuning range without introducing any increase in phase noise or power consumption. The VCO is tunable(More)
This paper proposes a complete analysis of quadrature-coupled LC oscillators. These oscillators operate off-resonance and for this reason, their phase noise worsens at increasing coupling strength. Since the coupling transistors raise the total power consumption, the noise-power product degrades further with respect to a stand-alone oscillator. On the other(More)
This paper describes an original computational procedure to extract the perturbation projection vector of oscillators by means of a frequency domain technique. A key feature of the method is that it relies on the periodic transfer function analysis, which is available in most circuit simulators, and thus it can easily be exploited by oscillator designers.(More)
— Amplitude-to-phase-noise conversion due to varactors can severely limit the close-in phase noise performance in LC-tuned oscillators. This work proposes a rigorous analysis of this phenomenon, which highlights the fundamental limitations of single-ended tuned and differentially-tuned diode varactor configurations. The back-to-back varactor topology is(More)
—This paper presents a digital scrambling technique to improve the linearity of flash time-to-digital converters (TDCs) with sub-gate-delay time resolution. Thanks to this approach, a flash TDC using N time arbiters behaves as a quasi-stochastic TDC with an equivalent number of samples equal to N 2 , at the negligible area cost of doubling the number of(More)