S. Ver Hoeye

Analytical comparison between time- and frequency-domain techniques for phase-noise analysis

In the literature, different techniques have been presented for the phase-noise analysis of free-running oscillator circuits. In order to give some insight into the relationships existing between them, an analytical comparison is carried out in this paper between three different approaches. Two of them are time-domain approaches, based on Floquets theory and the impulse sensitivity function, respectively, and the third one is the carrier modulation approach, in frequency domain. The application of Floquets theory enables the calculation of periodic sensitivity functions to the noise perturbations. Here, the possibility to determine these functions through harmonic balance is demonstrated. This allows applying the whole stochastic characterization of phase noise, obtained from time-domain analysis, to circuits simulated through harmonic balance. For illustration, calculations in a cubic-nonlinearity oscillator are presented.

Analysis of noise effects on the nonlinear dynamics of synchronized oscillators

The higher sensitivity to noise of nonlinear systems near the onset of instability is analyzed here. The analysis is particularized to synchronized oscillators, studying the influence of the proximity to Hopf and Saddle-Node bifurcations. The calculations are compared with former scaling relationships and with results from time-domain integration. The average shift of bifurcation points due to noise perturbations is also analyzed. Two examples are shown: a cubic-nonlinearity oscillator and a 5 GHz hybrid oscillator, for experimental verifications.

New nonlinear design tools for self-oscillating mixers

New nonlinear design tools for self-oscillating mixers are presented here, with the aim to increase the designers control over their behavior. The new tools enable fixing the self-oscillation frequency and selecting the optimum self-oscillation amplitude for maximum conversion gain. They can also be applied for the optimized design of harmonic self-oscillating mixers. Using bifurcation-theory concepts, it has been possible to increase the input-power range with self-oscillating-mixer operation. A self-oscillating mixer with 5.5 GHz input frequency has been designed and simulated obtaining very good agreement with the experimental results.

Sub-Harmonic and Rational Synchronization for Phase-Noise Improvement

In an injected oscillator, synchronization bands (or Arnold tongues) are theoretically obtained at rational ratios between the frequencies of the generator and the self-oscillation. Here an in-depth analysis of this phenomenon is carried out. A simple and accurate technique is presented for the harmonic-balance prediction of the subharmonic and rational synchronization bands. Two designs of a synchronized MESFET-based oscillator at the respective ratios ¿ and a ¿ are presented, with the simulation and measurement of the steady-state regime. A good improvement of the free-running oscillator phase noise has been achieved.

Techniques for oscillator nonlinear optimization and phase-noise analysis using commercial harmonic-balance software

Two new techniques for microwave oscillator design are presented for user implementation on commercial harmonic-balance simulators: an easy-to-use nonlinear optimization technique and a phase-noise analysis technique that makes use of the impulse-sensitivity function. This method is implemented for the first time on a harmonic-balance simulator. Simulation results of a MMIC VCO in the Ku-band have been compared with measurements.

Receiving Polarization Agile Active Antenna Based on Injection Locked Harmonic Self Oscillating Mixers

A polarization agile active antenna with phase shifter elements based on injection locked third harmonic self oscillating mixers is presented. This phase shifting topology provides the double functionality of continuous range phase shifter and downconverter. The phase shift value introduced by each circuit can be easily tuned through a DC voltage within a theoretical continuous range of 450° . The behavior of the isolated phase shifter circuit is studied, both as a function of the control voltage and versus frequency, through harmonic balance and envelope transient simulations. The polarization tuning performance of the complete active antenna is simulated, analyzing the impact of the operating parameters of the phase shifter on the overall behavior. A receiving polarization agile antenna with an input frequency band centered at 11.25 GHz and an output frequency band centered at 1.5 GHz has been manufactured for the experimental validation of the simulated results. A continuous range of polarization tuning has been observed, including two orthogonal linear polarizations along with left hand and right hand circular polarization.

Nonlinear analysis of a microwave synthesizer based on a sampling-phase detector

A microwave synthesizer operating at 6.52 GHz and based on a sampling-phase detector has been designed and simulated. The employment of nonlinear analysis tools has enabled an in-depth study of the system dynamics. Hold-in and lock-in bands are determined in a direct and accurate way through the use of the Poincare-map technique. The nonlinear analysis has also made possible the a-priori determination of the loop-filter and VCO characteristics for a good performance in terms of phase noise and loop dynamics.

Nonlinear Analysis of Mutually Coupled Harmonic Self-Oscillating Mixers

In this paper, a phase array based on coupled harmonic self-oscillating mixers (HSOMs) is presented for its application in a receiving antenna array. Nonlinear analysis is realized in a 4 x 1 element array based on injection-locked and mutually coupled HSOMs. Each element of the phase array provides the double functionality of variable phase shifters and downconverters. The ranges of synchronized operation and the corresponding phase shifts provided by the individual HSOMs are analyzed versus the circuit parameters. The phase variation of the coupled HSOMs is calculated for different operation points of the innermost HSOMs of the array. A 4 X 1 element array has been manufactured for the experimental validation of simulated results.