Stability and Bifurcation Analysis of Self-Oscillating Quasi-Periodic Regimes

IEEE Trans. Microwave Theory Techn.

Pontón

Sancho

et al. 2017

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Abstract-A methodology is presented to analyze the impact of the termination load on the oscillation frequency and output power of autonomous circuits. Variations of this load can also lead to an extinction of the oscillation signal, due to their effect on the impedance seen by the active device(s). The new methodology enables an efficient analysis and mitigation of the pulling effects, in the case of undesired output mismatch, as well as an efficient oscillator synthesis in large-signal conditions, for specified values of oscillation frequency and output power. The method is based on the calculation of constant-amplitude and constant-frequency contours, traced in the Smith chart. Oscillation extinctions and some forms of hysteresis can be predicted through the inspection of these contours. However, the stability properties will generally depend on the frequency characteristic of the termination impedance. In an oscillator synthesis, the selected impedance, providing the specified values of oscillation frequency and output power, must be implemented in order to guarantee a stable solution. The dependence of the phase-noise spectral density on the particular implementation is predicted combining an analysis based on the variance of the phase deviation with the conversionmatrix approach.

Section: A Hysteresismentioning

confidence: 97%

Analysis of Output Loading Effects in Autonomous Circuits

IEEE Trans. Microwave Theory Techn.

Pontón

Sancho

et al. 2017

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“…In Class-D amplifiers, a high amplitude signal (switching signal) at the frequency f o makes the transistors switch between on-and off-stages and the output voltage has a rectangular waveform. In the case of a SOPA, the Class-D amplifier [32][33][34] is inserted into a feedback loop (Fig. 8), which should enable an oscillation at f o , with no need for an extra source.…”

Section: Envelope Transientmentioning

confidence: 99%

“…Fig. 9 presents the output power spectrum obtained with WCDMA-like signal centred at 200 MHz [34]. It shows the dithering effect of the higher frequency oscillation.…”

Section: Envelope Transientmentioning

confidence: 99%

Nonlinear microwave simulation techniques

2015 Integrated Nonlinear Microwave and Millimetre-Wave Circuits Workshop (INMMiC)

2015

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-The design of high performance circuits with short manufacturing cycles and low cost demands reliable analysis tools, capable to accurately predict the circuit behaviour prior to manufacturing. In the case of nonlinear circuits, the user must be aware of the possible coexistence of different steady-state solutions for the same element values and the fact that steadystate methods, such as harmonic balance, may converge to unstable solutions that will not be observed experimentally. In this contribution, the main numerical iterative methods for nonlinear analysis, including time-domain integrations, shooting, harmonic balance and envelope transient, are briefly presented and compared. The steady-state methods must be complemented with a stability steady-state analysis to verify the physical existence of the solution. This stability analysis can also be combined with the use of auxiliary generators to simulate the circuit self-oscillation and predict qualitative changes in the solution under the continuous variation of a parameter. The methods will be applied to timely circuit examples that are demanding from the nonlinear analysis point of view.

“…When increasing (decreasing) the parameter from a low (high) value the circuit initially operates in section 1 (section 3) and jumps to section 3 (section 1) at the turning point T 1 (T 2 ). In most cases, the hysteresis is due to an expansion of the circuit negative resistance in a certain interval of the excitation amplitude [5], which enables the fulfilment of the steady-state conditions for three distinct amplitude values. In most previous works, hysteresis was undesired, so several simulation tools [1]- [3] were proposed for its accurate prediction at the design stage.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Synthesis of Hysteresis Loops in an Oscillator Frequency Characteristic

IEEE Trans. Microwave Theory Techn.

Melville²,

Ramírez

2019

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A methodology for the analysis and synthesis of multiple hysteresis loops in the frequency characteristic of a voltage-controlled oscillator (VCO) is presented. This is achieved through the coupling of an oscillator inductance to multiple external (passive) resonators, with resonant frequencies in the tuning range of the VCO. A possible application to the implementation of a compact chipless Radio Frequency Identification (RFID) system is explored, using the oscillator as a reader and placing the external resonators in the tag. The system takes advantage of the high sensitivity to the tag resonances in the presence of hysteresis, which leads to vertical jumps in frequency versus the tuning voltage. A desired bit pattern would be encoded in the tag by enabling or disabling passive resonances at a sequence of frequencies. In the practical realization, the inductors in the oscillator and the external board are implemented through spiral inductors so that the resonators in the VCO and the tag have strong broadside coupling. The coupling effect is modeled through electromagnetic simulations, from which a linear admittance, representing the coupled subnetwork, is extracted. The multi-hysteresis oscillator characteristic can also be obtained experimentally through a new methodology able to stabilize the physically unstable sections without altering their steady-state values. Different demodulation methods for reading the tag are discussed.