Dual-mode Oscillator Research Articles

Theoretical analysis of the buried heterostructure laser for stable dual-wavelength generation

Stable dual-wavelength emission from a laser is desirable for microwave signal generation using the optical heterodyning method. As both optical wavelengths are generated from the same cavity, the phase noise of the generated microwave signal is minimized. In this work, we exploit the inherent birefringence in the buried heterostructure semiconductor laser to generate dual polarized modes. We carefully analyze the mode competition between various modes in the cavity and propose the desirable gain modification conditions for stable dual mode oscillations when the laser is operating near the threshold. We show that the required asymmetry in the gain for two stable modes can be obtained from the mode confinement factors and facet losses. We also show the applicability of our results to a homogeneously broadened multimode laser.

Nonlinear feedback self-excitation of modal oscillations in a class of under-actuated two degrees-of-freedom mechanical systems

Recently, scientists have utilized self-excited oscillations in many mechanical and micromechanical applications and accordingly, several experimental and theoretical research activities have been undertaken with the objective of artificially inducing self-excited oscillation in mechanical systems. This paper considers some theoretical aspects of generation of self-excited oscillation in a two degrees-of-freedom under-actuated spring–mass–damper system by centralized nonlinear feedback. The control force depends on the response of both masses. The proposed control law is slightly general in nature as it entails both collocated and non-collocated control as special cases. The response of the nonlinear feedback control is studied with the help of the method of averaging. The present study shows that by appropriately selecting the control gains it is possible to excite the desired mode(s) of oscillation irrespective of initial conditions. Even it is possible to excite dual mode oscillation having the characteristics of quasiperiodic oscillations. The theoretical analysis of the dynamics of the system with the control is validated by simulation results, performed in MATLAB Simulink.

Upconversion Loop Oscillator Axion Detection Experiment: A Precision Frequency Interferometric Axion Dark Matter Search with a Cylindrical Microwave Cavity

First experimental results from a room-temperature tabletop phase-sensitive axion haloscope experiment are presented. The technique exploits the axion-photon coupling between two photonic resonator oscillators excited in a single cavity, allowing low-mass axions to be upconverted to microwave frequencies, acting as a source of frequency modulation on the microwave carriers. This new pathway to axion detection has certain advantages over the traditional haloscope method, particularly in targeting axions below 1 μeV (240MHz) in energy. At the heart of the dual-mode oscillator, a tunable cylindrical microwave cavity supports a pair of orthogonally polarized modes (TM_{0,2,0} and TE_{0,1,1}), which, in general, enables simultaneous sensitivity to axions with masses corresponding to the sum and difference of the microwave frequencies. However, in the reported experiment, the configuration was such that the sum frequency sensitivity was suppressed, while the difference frequency sensitivity was enhanced. The results place axion exclusion limits between 7.44-19.38neV, excluding a minimal coupling strength above 5×10^{-7} 1/GeV, after a measurement period of two and a half hours. We show that a state-of-the-art frequency-stabilized cryogenic implementation of this technique, ambitious but realizable, may achieve the best limits in a vast range of axion space.

Peak-power enhancement of a cavity-dumped cesium-vapor laser by using dual longitudinal-mode oscillations.

We have performed cavity dumping of a diode-pumped alkali laser (DPAL) and have observed a saw-like structure in the pulse waveform that appears to be caused by interference between two or more longitudinal modes. We have confirmed that multimode oscillations are caused by spatial hole burning, and the largest peak was seen when only two oscillation modes were present. This phenomenon may be useful for enhancing the cavity dumping of the DPAL, but it was not always observed. Therefore, we developed a numerical simulation to predict the number of longitudinal modes excited under a given set of conditions and provides guidelines to facilitate dual-mode oscillation. Using these guidelines, we have obtained a pulse with a peak power of 250 W, which is higher than the average power circulating in the cavity and is a 38-fold enhancement of the continuous-wave (CW) output.

Single VDGA-Based Dual-Mode Multifunction Biquadratic Filter and Quadrature Sinusoidal Oscillator

This article relates to the realization of voltage-mode and/or current-mode multifunction biquadratic filter and quadrature oscillator circuits each using one voltage differencing gain amplifier (VDGA), two resistors and two grounded capacitors. The proposed dual-mode filter having one output and three inputs can provide the three standard biquadratic transfer functions with both voltage and current output filter responses simultaneously. It also has the independent tuning of the angular resonance frequency and the quality factor . With a slight modification of the proposed filter, a new dual-mode quadrature sinusoidal oscillator can be obtained. The proposed quadrature oscillator provides orthogonal resistive/electronic control of both oscillation condition and oscillation frequency. Non-ideal and parasitic conditions are also examined and their effects on the circuit performance are discussed. In order to confirm the theory, several computer simulation results with PSPICE program are given .

Novel current mode universal filter and dual-mode quadrature oscillator using VDCC and all grounded passive elements

ABSTRACTThe paper introduces a universal filter operating in current mode and a quadrature oscillator operating in current and voltage mode, employing Voltage Differencing Current Conveyor as active device along with all grounded passive elements. Apart from providing all five filter responses, i.e. low pass, high pass, band pass, band reject and all pass, the filter configuration also supports independent tunability of quality factor. The oscillator configuration can be easily realised with slight modifications in filter circuit, and features like low component count, use of grounded capacitors for supporting efficient integrated circuit implementation and availability of explicit current outputs are witnessed in both the devised networks. In the oscillator, network’s condition and frequency of oscillation can be independently tuned. For practical validation of the proposed network, PSPICE simulation software is used. The simulation results include two sets of outputs, one using CMOS (Complmentary Metal Oxide Semiconductor) implementation of Voltage Differencing Current Conveyor (VDCC) and another using off the shelf IC (Integrated Circuit) implementation of VDCC.

Transmission Line Tunable Resonators With Intersecting Resonance Regions

A new property of tunable lumped-distributed circuits, namely, the intersection effect of resonant regions of two resonators with variable capacitors, is observed. As is known, the resonant regions of widely used resonators with varactors are separated by frequency intervals from each other. The construction of the proposed resonators is based on the resonance equations. One resonator is a loop hairpin stepped-impedance resonator with one capacitor. In this resonator, a controlled regime of dual-mode oscillations is realized, when the even and odd modes of the oscillations can change places. For this a one variable capacitor is used only. Another resonator is a symmetrical stepped-impedance resonator with two capacitors at the ends. Its resonance regions for several oscillations with frequencies ${f} _{0}$ , ${f} _{1}$ , ${f} _{2}$ intersect each other. This effect allows tuning in a very wide frequency range with simultaneous use of these oscillations. The results of the measurements and simulation for the reconfigurable microstrip dual-mode filter with one capacitor are presented.

Dual transduction on a single sensor for gas identification

Poor selectivity is one important limitation of gas sensors based on chemisorption or physisorption. This poor selectivity is usually tackled through the use of a gas sensor array, whose individual elements have diverse selectivity. Gas identification can be achieved by analyzing the unique response patterns of the sensor array. However, such an approach is costly due to its complexity. In this paper, we investigate an alternative solution enabling single sensor gas identification through the integration of two transduction mechanisms in one sensor. We demonstrate this approach through the design of a novel dual transduction gas sensor capable of simultaneously detecting gas-induced variations in the mass and resistance of the sensing material. The relative independence of acquired gravimetric and resistive responses is shown to enable subsequent gas identification. In addition, the proposed approach can also improve the overall limit of detection (LOD) to different gases by exploiting the individual responses with the best LODs. The proposed dual transduction gas sensor was implemented by integrating a film bulk acoustic wave resonator (FBAR) together with interdigitated electrodes. A configurable dual-mode oscillator circuit is also proposed to simultaneously read-out both responses from the sensor.

Phase Transition Analysis of Dual-Mode Standing-Rotary Traveling-Wave Oscillator

In this paper, a dual-mode standing-rotary traveling-wave oscillator (S-RTWO) is analyzed. In order to force the conventional RTWO to oscillate in the standing wave mode, an ideal switch is used for shorting two differential nodes of the RTWO circuit. The closed-form equations, which describe the transitions of phases between the standing wave mode and the rotary traveling wave mode of the oscillator, are derived, and the delays of transitions between two modes of the oscillator are extracted by using these equations. Besides, the oscillation start-up delay is analyzed, and the closed-form equation for the start-up delay is obtained in terms of circuit elements. Finally, our theoretical results are compared with appropriate and accurate simulations to evaluate the validity of the delays analysis and the accuracy of the closed-form equations. Simulations of the dual-mode oscillator have been done in a 0.18- $\mu \text{m}$ CMOS technology with a 1.8-V supply voltage. The evaluations show very good agreement between analytical equations and simulation results, and confirm the validity and accuracy of the delays analysis.

Tuning Range Extension of a Transformer-Based Oscillator Through Common-Mode Colpitts Resonance

In this paper, we propose a method to broaden a tuning range of a CMOS LC -tank oscillator without sacrificing its area. The extra tuning range is achieved by forcing a strongly coupled transformer-based tank into a common-mode resonance at a much higher frequency than in its main differential-mode oscillation. The oscillator employs separate active circuits to excite each mode but it shares the same tank, which largely dominates the core area but is on par with similar single-core designs. The tank is forced in common-mode oscillation by two injection locked Colpitts oscillators at the transformer’s primary winding, while a two-port structure provides differential-mode oscillation. An analysis is also presented to compare the phase noise performance of the dual-core oscillator in common-mode and differential-mode excitations. A prototype implemented in digital 40-nm CMOS verifies the dual-mode oscillation and occupies only 0.12 mm2 and measures 56% tuning range.

A coupled-inductor dual-mode switched voltage-controlled oscillator using GaN-on-Si HEMT technology

ABSTRACTA coupled-inductors dual-mode switch cross-coupled pair voltage-controlled oscillator (VCO) was presented, adopting GaN-on-Si high-electron-mobility transistor technology. The coupled inductors create two resonant frequencies that cover a wide frequency range. The two continuous bands were achieved by using coupled inductors, and the fine-tuning is controlled by varactors. The low and high bands of the VCO were 2.77–3.11 GHz and 3–3.28 GHz, in the Vc range between 10 and 17 V, respectively, which corresponds to a 16.7% (510 MHz) tuning range. The lowest phase noise was −123 dBc/Hz at an offset frequency of 1 MHz, and the highest output power was 17.7 dBm using a 7.5-V power supply.

Design of Oscillation Control Loop With Coarse-Precision Mode Transition for Solid-State Resonant Gyroscope

This paper presents a dual mode oscillation control loop design for a solid-state hemispherical resonator gyroscope (HRG) which uses the hemispherical vibrating shell for detecting the Coriolis force. A desirable control loop needs to be robust, fast, and also to have small driving and frequency noises which may cause significant errors, such as angular random walk. To design a fast and robust oscillation loop for precision gyroscope, a novel approach using a sequential resonance control mode transition is proposed in this paper. The coarse resonance control mode principally consists of phase shifter and limiter, which provides fast startup and tolerant tracking performances. The precision mode uses phase-locked loop for the sake of precision tracking performance. In addition, a theoretical analysis on the designed control loop considering mode transition is presented. In this paper, the tracking performances of the proposed loop are demonstrated via both simulation and experiments. The experimental results using a fabricated HRG verified the effectiveness of the proposed method.

Microwave resonators with dual-mode oscillations

Analysis of microwave resonators with dual-mode oscillations is conducted. A new type of resonators is discovered in which dual-node oscillations are observed. It represents a half-wave resonator with a short-circuit in the middle part. The length of such a resonator is twice less than the length of a widely used ring resonator. It is shown that in resonators of the loop type combined frequency tuning of dual-mode oscillations is accomplished using capacity and inductance. In the loop-type resonators with a stub frequency tuning of dual-mode oscillations is accomplishing with two capacities synchronously changing their values according to a specific law. Resonance equations are obtained.

Dual-band transformer resonator oscillator with common-mode gain control

A new dual-mode oscillation scheme that adopts a transformer resonator is proposed. Switch-controlled common- and differential-mode operations enable the proposed oscillator to generate low and high frequency band, respectively. Simulated results for the proposed oscillator designed in CMOS 0.13 µmm process show dual-band frequencies of 2–2.87 and 5.75–9.36 GHz at the mode switch-on and switch-off, respectively, while dissipating 2.5 mA at 1.2 V supply.

Differential two-signal picosecond-pulse coherent anti-Stokes Raman scattering imaging microscopy by using a dual-mode optical parametric oscillator

We propose and demonstrate a novel differential two-signal technique of coherent anti-Stokes Raman scattering (CARS) imaging microscopy using a picosecond (ps) optical parametric oscillator (OPO). By adjusting a Lyot filter inside the cavity, we operated the OPO oscillating in two stable modes separated by a few nanometers. The CARS images generated by the two modes are separated by a spectrograph behind the microscope setup, and their differential image is directly obtained by balanced lock-in detection. The feasibility of the technique is experimentally verified by imaging micrometer-sized polystyrene beads immersed in water.

Transformer-Based Dual-Mode Voltage-Controlled Oscillators

In this brief, we propose to use a transformer-based resonator to build a dual-mode oscillator, e.g., a system capable of oscillating at two different frequencies without recurring to switched inductors, switched capacitors, or varactors. The behavior of the resonator configured as a one-port and a two-port network is studied analytically, and the dependence of the quality factor on the design parameters is thoroughly explored. These results, combined with the use of traditional frequency tuning techniques, are applied to the design of a wide-band voltage-controlled oscillator (VCO) that covers the frequency range 3.6-7.8 GHz. The performance of the designed VCO, implemented in a digital 0.13-mum CMOS technology, has been studied by transistor-level and 2.5D electromagnetic simulation (Agilent Momentum). A typical phase noise performance at 1-MHz offset of -104 dBc/Hz has been predicted, while the power consumption ranges from 1 to 8 mW, depending on the VCO configuration

Room temperature dual-mode oscillator—first results

An analysis is presented for a room temperature dual-mode oscillator (patent pending) utilising a single sapphire resonator in which two orthogonally polarised whispering gallery modes are excited. The temperature dependence of the 3.39 GHz beat frequency was annulled near 304 K. An Allan deviation of 8×10−12 was measured at 1s.

CMOS LC-ring oscillator with adaptive purity control

An LC-tuned/LC-ring dual-mode oscillator structure is presented to implement an adaptive purity control scheme and provide an optimisation process between the interference immunity and the current consumption. This dual-mode reconfigurable oscillator is fabricated in a 0.18 µm CMOS process and achieves the measured phase-noise controllability of 11 dB/Hz.

High-Q frequency–temperature compensated solid-nitrogen-cooled resonator-oscillators: first results

Experimental results for two solid-nitrogen-cooled microwave resonator oscillators are presented. The Allan deviation was measured to be just less than 2×10−13 for 10 s<τ<100 s in the dual-mode oscillator and 2–3×10−13 for 1 s<τ<6 s in the sapphire-rutile composite design.

The dual-mode frequency-locked technique for the characterization of the temperaturecoefficient of permittivity of anisotropic materials

In this work we present a new method for obtaining accurate characterization of thetemperature coefficient of permittivity (TCP) of an anisotropic crystal, which we call thedual-mode frequency-locked technique. The technique requires precise simultaneousfrequency measurements of two orthogonally polarized modes as a function oftemperature. This was achieved by configuring a sapphire resonator as a pound-lockeddual-mode oscillator and measuring the frequencies with a frequency counter, whilesimultaneously recording the temperature with a platinum thermometer. From the twodata files of frequency versus temperature, and knowledge of the electric anddimensional filling factors (obtained from finite element analysis), it was possible tocalculate the integrals of the TCP without resorting to polynomial fits. Thisresulted in a precise model of the components of the TCP between 50 and 77 Kfor sapphire. The model is accurate enough to predict, within a few kelvin, thefrequency turnover temperatures of the difference frequency of a dual-mode oscillator.