High-Q active resonators using amplifiers and their applications to low phase-noise free-running and voltage-controlled oscillators

This paper presents a new technique to design high-Q active resonators. The active resonators are then used in the design of low phase-noise oscillators. The proposed new technique uses an amplifier to generate a negative resistance, which compensates for the resonator losses and increases the Q factor. The active resonator using this technique shows a high loaded Q factor of 548.62 from measurement at the fixed 10-GHz resonant frequency. Considerations to design a voltage tunable active resonator is given and measurements show that the loaded Q factors exceed 500 with a 120-MHz tuning range. A low phase-noise free-running and voltage-controlled oscillator (VCO) were designed as an application of the proposed active resonators. The phase noise of the free-running oscillator using the active resonator is -114.36 dBc/Hz at 100-kHz offset, which is 14 dB lower than the phase noise of the passive resonator oscillator. In the case of a VCO using the active resonator, the phase-noise performance is below -110 dBc/Hz over the whole tuning range, which is lower 13 dB compared to the passive resonator VCO. The total dc power consumptions are approximately 500 mW.     

YIG Resonator Circuit with Isolator Property and its Application to a Gunn Diode Oscillator

This paper presents the analysis and experiment of a newly developed YIG resonator circuit with isolator property, which is constructed with a YIG sphere, three coupling loops, and a 3-dB stripline directional coupler. This YIG circuit can be used advantageously as the toning element of a magnetically tunable oscillator. The circuit has an advantage in preventing frequency pulling and the variation of output power level of the oscillator due to a change in load condition because of the resonator circuit having isolator property at the same time. The design procedure and experiment of a magnetically tunable Gunn diode oscillator with the YIG circuit is also shown. It has been confirmed that the YIG circuit when applied to a tunable oscillator is quite useful.     

S波段低相噪同轴介质压控振荡器设计

运用串联反馈振荡器理论设计了一个工作于S波段的低相噪同轴介质压控振荡器。首先分析了同轴介质谐振器的理论以及串联反馈振荡器的工作原理,然后在高频电磁仿真软件HFSS和ADS中进行仿真和设计。为了实现电调谐,将变容管合理地加入振荡器,最终设计完成了一个S波段的低相噪同轴介质压控振荡器。通过对实物成品的测量和调试表明,此压控振荡器达到了预定的技术指标,各项性能良好。测试结果:工作频率为2.075~2.250 GHz,调谐范围为1.75 GHz,输出功率≥11 dBm,谐波抑制度≥23 dBc,相位噪声优于-133 dBc/Hz@100kHz。     

Piezoelectric-transducer-controlled tunable microwave circuits

This paper introduces a new method to tune microwave circuits of phase shifters, filters, resonators, and oscillators, controlled by a piezoelectric transducer (PET) with computational and experimental results. An optimized PET-controlled phase shifter is demonstrated to operate up to 40 GHz with a maximum total loss of 4 dB and phase shift of 480°. PET-controlled tunable bandpass filter, ring resonator, and one-dimensional photonic-bandgap resonator show a very wide tuning bandwidth of 17.5%-28.5% near 10 GHz with little performance degradation. A new PET-controlled or voltage-controlled dielectric-resonator oscillator (DRO) is demonstrated with a tuning bandwidth of 3.7% at the center frequency of 11.78 GHz. The tuning bandwidth is slightly less than that of a mechanical tuning using a micrometer-head-controlled tunable DRO with a tuning bandwidth of 4.7%. The new tuning method should have many applications in monolithic and hybrid microwave integrated circuits     

Wide tunable double ring resonator coupled lasers

A double ring resonator coupled laser (DR-RCL) is proposed and analyzed in this letter. Benefiting from the uniform peak transmission, narrow bandwidth and other superior characteristics of traveling wave supported high-Q resonators, DR-RCLs offers many promising advantages over the conventional tunable lasers, including ultra wide wavelength tuning range, high side mode suppression ratio, uniform threshold and efficiency, narrow linewidth, low frequency chirp, and simple fabrication. A DR-RCL with a moderate optical loss ~10 dB/cm in the ring resonators can achieve a wavelength tuning enhancement of ~50. With such a large tuning leverage, DR-RCLs could utilize the electrooptic effects to achieve ultrafast tuning speed with a wide tuning range covering the material gain bandwidth     

Design of a negative conductance dielectric resonator oscillator for X-band applications

An X-band tunable microwave low-phase noise planar oscillator employing a novel-fed dielectric resonator (DR) with a single transistor has been investigated and realized. A ZrSnTi oxide composite ceramic-based DR with dielectric permittivity of 95 enclosed in a metallic cavity with an unloaded Q factor of 5,000 at 10 GHz is proposed. The resonant frequency affinity with respect to geometric parameters is established by using the compensation technique based on dual negative conductance feedback, the outputs of which are combined via a Wilkinson power divider (WPD). The feedback parallel-coupled DR oscillator is incorporated into a laminate microwave board using the photolithographic technique. The oscillator includes a pseudomorphic low noise amplifier based on a high-electron-mobility transistor. Hence, the proposed oscillator with mechanic tuning is measured, and the results show that DR resonates at TE _01δ mode with frequency of 10 GHz. The measured phase noise of the oscillator is –81.03 dBc/Hz at a 100 kHz offset.     

Dual electric and magnetic frequency tuning of coupled oscillations in a composite magnetodielectric resonator

The possibility of dual magnetic and electric tuning of resonance frequencies of the electrodynamic structure consisting of dielectric resonator and the epitaxial film of Yittrium-Iron Garnet (YIG)- lead zirconate titanate (LZT) heterostructure has been shown. The coupled electromagnetic-andspin oscillations of dielectric resonator and epitaxial YIG film were theoretically and experimentally investigated. The experiments revealed the possibility of implementing the electric frequency tuning of coupled oscillations of a composite magnetodielectric resonator. This possibility is determined by induced elastic stresses in the epitaxial YIG film. A theoretical model is proposed for calculating the frequency shift of coupled oscillations caused by the electric field applied to the piezodielectric layer. It is shown that the basic Q-factor of composite resonator and the range of electric frequency tuning of hybrid oscillations increase with the reduction of the magnetic bias field.     

四通道AOTF射频驱动功率源

声光可调滤光器（ＡＯＴＦ）是未来全光网络中实现波长路由选择的首选器件。具有独特的多通道操作功能，可同时选择多个波长及快速调谐。要实现ＡＯＴＦ的可调波长选路功能，对驱动功率源有较高的要求。本文介绍了我们研制的一种可调谐通道射频功率源，其中采用声表面波谐振器制作的频率源具有较大的调谐范围和较高频率稳定性。瞬时频率稳定度达到１０＾－８；单通道输出功率可达１Ｗ，能满足ＡＯＴＦ的操作要求。     

Widely tunable Mach-Zehnder interferometer laser with improved tuning efficiency

A successful realisation of widely tunable lasers based on a new design is presented. The lasers use a vertically integrated, electronically tunable Mach-Zehnder interferometer inside the resonator to select single Fabry-Perot resonances. With single-current tuning, a tuning range of 35 nm is experimentally demonstrated.     

基于基片集成波导谐振器的压控振荡器设计

设计了一种基于基片集成波导谐振器的X波段压控振荡器。首先分析了串联反馈式振荡器以及基片集成波导谐振器的理论,然后在高频电磁仿真软件ADS中进行仿真和设计,并通过将变容管合理地引入谐振器,实现了电调谐的目的。最终设计完成了一个工作于X波段的基片集成波导压控振荡器。此压控振荡器与传统的介质压控振荡器(DRO)相比,具有稳定性高、平面化以及成本低的优点。由于采用了ADS中的联合仿真功能进行振荡器的设计,仿真结果的准确性得到了提高,减小了实物的调试工作量。测试结果为:工作频率为7 GHz,调谐范围为30 MHz,输出功率≥7 dBm,谐波抑制度≥22 dBc,相位噪声优于-106 dBc/Hz@100 kHz。     

A Differentially-Tuned Voltage ControlledOscillator Using Symmetric Transformer

This letter proposes a new voltage controlled oscillator (VCO) topology that cancels common-mode noise by adoption of differential tuning varactor. To suppress common mode noise effectively, a symmetric three-coil transformer is proposed as a differential tuning resonator. The measured phase noise shows -128.7 dBc/Hz at 1 MHz offset frequency from the 1.2 GHz oscillation frequency. Over the whole frequency range, common-mode noise rejection is larger than 36 dB. Measured tuning range of the proposed VCO is about 204 MHz from the 1.18 GHz to 1.38 GHz while dissipating 1.2 mA at 1.8 V power supply.     

An X-band integrated circuit FET oscillator with dielectric resonator stabilization

Experimental results are presented for the performance of a MIC common drain GaAs FET oscillator and are compared with the performance of the same oscillator stabilized by using a high Q. temperature compensated dielectric resonator made from barium nonatitanate. The unstabilized oscillator gave 85 mW of Rf power at an efficiency of 20%. whilst the compensated oscillator gave 46 mW of power at an efficiency of 12%. with a line width of only 0.3 MHz as measured at 60 dB below the peak. Over the temperature range 0 to 60°C the frequency of the stabilized oscillator changed only 5 MHz, compared t0 the 30 MHz change found in unstabilized oscillators. Mechanical tuning was easily achieved, and careful choice of coupling between the resonator and oscillator eliminated the hysteresis observed in the mode of oscillation of designs previously reported.     

YIG Oscillators: Is a Planar Geometry Better? (Short Papers)

Two yttrium-iron-garnet (YIG) oscillator technologies are compared: the more mature YIG sphere oscillator technology which is based on the uniform (resonant) precession of the electron spins in a small sphere of YIG, and the new planar YIG technology which utilizes the propagation of magnetostatic waves in an epitaxial film of YIG. The YIG sphere technology has been used for microwave oscillators for more than 25 years, but has two significant areas of difficulty in applications the alignment of the YIG sphere in the magnetic bias field coupling cavity requires great precision and the gain element requires a negative resistance element to sustain oscillation. The MSW technology is much newer and less well understood, but the resonator elements are fabricated using a 50- µm line width planar technology making it an appealing candidate. Both technologies are reviewed herein with regard to resonant element theory, temperature, and noise characteristics. New data and theory are presented on MSW resonator optimization.     

Electrooptic narrow linewidth wavelength tuning and intensity modulation of an erbium fiber ring laser

We report an electrically tunable fiber laser featuring a 50-channel wavelength switching capability with a 0.2 nm linewidth and -20 dB crosstalk. The laser consists of an Er-doped fiber resonator and an electro-optic TE-TM convertor used as a wavelength tunable filter. It allows wavelength tuning over a spectral range of 10 nm with a tuning rate of 0.05 nm/V and a linewidth of 0.06 nm.     

Octave-tunable miniature RF resonators

The development and testing of a miniaturized, high-Q, broadly tunable resonator is described. An exemplary device, with a center frequency that is continuously tunable from 1.2 to 2.6GHz, was tested in detail. Experimental results demonstrated a resonator Q of up to 380, and typical insertion loss of -1.9dB for a 25MHz 3-dB bandwidth. These resonators have been used to stabilize a broadly-tunable oscillator with phase noise of -132dBc/Hz at 100-kHz offset, with a center frequency tunable from 1.2-2.6GHz, and a tuning speed of 1GHz/ms.     

Analysis of a λ/4-phase-shifted doublephase-shift-controlled distributed feedback wavelength tunable opticalfilter

We have proposed a new λ/4-phase-shifted double phase-shift-controlled distributed feedback wavelength tunable optical filter structure. Theoretical analysis based on the transfer matrix method reveals that this filter can achieved a wavelength tuning range of 28.3 and 34.3 Å for the grating coupling coefficients of 6 and 10 mm, respectively. The filter has almost constant peak transmissivity (gain) of more than 30 dB within its tuning range, and its side-mode suppression ratio (SMSR) ranges from 15 to 34.7 dB     

1.5 μm phase-controlled distributed feedback wavelength tunableoptical filter

A 1.5-μm phase-controlled distributed feedback wavelength-tunable optical filter is studied. This is the first optical filter which controls the transmissivity (gain) and the transmission wavelength independently. Wavelength tuning range as wide as 43 GHz (3.4 Å) with high constant gain of 27 dB has been achieved. A five-channel wavelength selection with less than -10 dB crosstalk is expected with this filter. This device also operates as a wavelength tunable laser, and the wavelength tuning range as a laser is larger than as a filter. The reason is studied, and it is shown that suppression of the submodes is important to expand the wavelength tuning range     

On the spectral properties of widely tunable lasers usinggrating-assisted codirectional coupling

The analysis of mode-suppression-ratio (MSR) and wavelength tunability of widely tunable semiconductor lasers using grating-assisted codirectional-coupler (GACC) filters is considered. A tradeoff is found between tuning range and spectral purity when using this type of filter as an intracavity mode selector. It is shown that in order to improve the tuning range by a factor of 10 compared to a conventional tunable laser using distributed feedback reflectors (DBRs), one has to tolerate a MSR around 23 dB at 1 mW output optical power/facet for an ideal cavity design. Limitations imposed by the materials are illustrated with design curves based on a vertical-twin-guide structure in both GaAs and InP systems for lasing wavelengths at 0.98 and 1.55 μm, respectively