Electrical oscillators play a decisive role in integrated transceivers for wired and wireless communication systems. In this context the study of fully integrated differential VCOs has received attention. In this paper formulas for investigations of the stability as well as the amplitude of CMOS LC tank oscillators are derived, where an overall model of nonlinear gain elements is used. By means...

Based on a physical understanding of phase-noise mechanisms, a passive LC filter is found to lower the phase-noise factor in a differential oscillator to its fundamental minimum. Three fully integrated LC voltage-controlled oscillators (VCOs) serve as a proof of concept. Two 1.1-GHz VCOs achieve 153 dBc/Hz at 3 MHz offset, biased at 3.7 mA from 2.5 V. A 2.1-GHz VCO achieves 148 dBc/Hz at 15 MHz...

Frequency dividers are key components for frequency synthesis in wireless and wireline communication systems. Among different types of frequency dividers, LC-based injection-locked frequency dividers (ILFDs) feature highfrequency operation at low power consumption, but their locking range is quite narrow due to the high-Q nature of the resonator. Recently, design techniques to enhance the locki...

The structure and operating principle of ring oscillators (RO) have been described. The expression for the frequency of oscillation of a complementary metal oxide semiconductor (CMOS) delay cell based conventional ring oscillator is presented and propagation delay of the delay stages is calculated. The limitations of a conventional RO have been studied and a few techniques to overcome these lim...

An analysis is presented in this contribution to describe the steady-state amplitude of a CMOS LC Colpitts oscillator, as well as its response to small interferences. The problem of signal dependency of noise sources is also addressed. The general conclusions of the analysis are applicable to most LC oscillators. The procedure to perform a general analysis for an arbitrary LC oscillator is outl...

The effects of emitter degeneration on the oscillation frequency, output noise and tuning range of an emitter degenerated LC oscillator designed using bipolar transistors (BJT) is analyzed. Simulation results show increased oscillation frequency, tuning range and carrier-to-noise ratio (CNR). Design guidelines for emitter degenerated LC oscillators are also given.

An analysis of phase noise in differential cross-coupled tuned tank voltage controlled oscillators is presented. The effect of active device noise sources as well as the noise due to the passive elements are taken into account. The predictions are in good agreement with the measurements for different tail currents and supply voltages. The effect of the complementary cross-coupled pair is analyz...

An analysis of phase noise in differential crosscoupled inductance–capacitance (LC) oscillators is presented. The effect of tail current and tank power dissipation on the voltage amplitude is shown. Various noise sources in the complementary cross-coupled pair are identified, and their effect on phase noise is analyzed. The predictions are in good agreement with measurements over a large range ...

Multiphase clocks are very useful for realizing high-speed data processing systems with low-speed circuit elements. Triggered in sequence by equally-spaced N-phase clock signals, multiphase systems can achieve N-times higher operating frequencies than single-phase clocked systems. For this reason, multiphase clocks are often used for such applications as high-speed analog-digital converters (AD...

In this paper, an intuitive analysis of a phase noise reduction technique is done, and then a modified structure is proposed to achieve higher phase noise reduction than the original one. This method reduces the impact of noise sources on the phase noise by decreasing closed-loop gain in zero-crossings points and moving this high closed-loop gain to the non-zero-crossings points. This reduction...