Novel Phase Noise Reduction Method for CPW‐Based Microwave Oscillator Circuit Utilizing a Compact Planar Helical Resonator

This letter describes a compact printed helical resonator and its application to a microwave oscillator circuit implemented in coplanar waveguide (CPW) technology. The high quality (Q)‐factor and spurious‐free characteristic of the resonator contribute to the phase noise reduction and the harmonic suppression of the resulting oscillator circuit, respectively. The designed resonator showed a loaded Q‐factor of 180 in a chip area of only 40% of the corresponding miniaturized hairpin resonator without any spurious resonances. The fully planar oscillator incorporated with this resonator showed an additional phase noise reduction of 10.5 dB at a 1 MHz offset and a second harmonic suppression enhancement of 6 dB when compared to those of a conventional CPW oscillator without the planar helical resonator structure.     

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.     

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.     

Novel Utilization of the Dielectric Resonator Antenna as an Oscillator Load

For the first time, the idea of using the dielectric resonator antenna (DRA) as an oscillator load, named as DRAO, is presented in this paper. Unlike the conventional dielectric resonator oscillator (DRO), where the DR was merely used as a resonator, the DR here serves as both the radiating and oscillating loads. In addition, a compact tri-function hollow DR that incorporates the packaging function to the above dual function is demonstrated. The design procedures of the dual- and tri-function DRAOs are discussed. For demonstration, the DRAOs are designed at 1.85 GHz, which is used in the popular personal communications system (PCS). The return losses, input impedances, antenna gains, signal spectrums, phase noise, and radiation patterns of the two DRAOs are presented. It is shown that the loaded Q_L factor of the DRA can be increased by internally embedding a compact metallic cavity to the DR. It is found that with a higher loaded Q_L factor, the phase noise of the antenna oscillator using the hollow DRA (tri-function DRAO) is better than that using a solid DRA (dual-function DRAO).     

Cavity coupling structure for planar oscillators showing DR-likereflective characteristics

A new cavity coupling structure has been developed for low-phase noise oscillator applications. Unlike the conventional cavity coupling structures that show absorption at the resonant frequency, the new structure shows high reflection at resonance similar to dielectric resonators, making it suitable for the reflective oscillators. The fabricated cavity resonator showed a loaded Q-factor of 1200 and the X-band oscillator using the new resonator showed phase noise proper-ties of -57 and -83 dBc/Hz at 1 and 10 kHz offset, respectively. This is comparable to the best results of dielectric resonator oscillators using HEMTs at this frequency range     

A compact-size microstrip spiral resonator and its application to microwave oscillator

This letter presents a compact size microstrip spiral resonator and its application to a low phase noise oscillator. This resonator has stopband characteristics to be used in the series feedback oscillator topology. The whole circuit area of the proposed resonator is within 1/10 wavelength, which results in the reduction of the circuit area and cost. A 10-GHz oscillator incorporated with this resonator was designed, fabricated and measured. It shows low phase noise performance of -95.4-dBc/Hz at 100 kHz offset.     

基于高次谐波体声波谐振器的微波振荡器设计

基于高次谐波体声波谐振器(HBAR)的高品质因数(Q)值和多模谐振特性,设计了Colpitts和Pierce两种形式的微波振荡器。采用HBAR与LC元件组成谐振回路的方法,与放大电路构成反馈环路直接基频输出微波频段信号。Colpitts振荡器输出信号频率为980 MHz,信号输出功率为-4.92dBm,信号相位噪声达-119.64dBc/Hz@10kHz;Pierce振荡电路输出信号频率达到2.962GHz,信号输出功率为-9.77dBm,信号相位噪声达-112.30dBc/Hz@10kHz。     

Hybrid high temperature superconductor/GaAs 10 GHz microwaveoscillator: temperature and bias effects

Hybrid YBa₂Cu₃O_7-x superconductor/GaAs microwave oscillators have been designed, fabricated and characterized. The planar oscillators were built on a single 10 mm×10 mm LaAlO₃ substrate. The active elements in the hybrid oscillators were GaAs MESFETs. A ring resonator was used to select and stabilize the frequency. A superconducting ring resonator had a loaded Q at 77 Kg which was 8 times larger than the loaded Q of a ring resonator fabricated out of copper. S-parameters of the GaAs FET were measured at cryogenic temperatures and used to design the oscillator which had a reflection mode configuration. The transmission lines, RF chokes and bias lines were all fabricated from YBa₂Cu₃ O_7-x superconducting thin films. The performance of the oscillators was measured as a function of temperature. The rate of change of the frequency as a function of temperature was smaller for an oscillator patterned from a pulsed laser deposited film than for an oscillator patterned from a sputtered film. As a function of bias at 77 K, the best circuit had an output power of 11.5 dBm and a maximum efficiency of 11.7% The power of the second harmonic was 25 dB to 35 dB below that of the fundamental, for every circuit. At 77 K, the best phase noise of the superconducting oscillators was 68 dBc/Hz at an offset frequency of 10 kHz and less than -93 dBc/Hz at an offset frequency of 100 kHz. At an offset frequency of 10 kHz, the superconducting oscillator had 12 dB less phase noise than the copper oscillator at 77 K     

射频MEMS封装振荡器的稳定性研究

文章介绍了一种由MEMS圆盘谐振器和低噪声反馈电路构成的射频振荡器。MEMS谐振器具备高Q值,使得振荡器表现出良好的频率稳定性和低相位噪声。采用低成本的金锡键合工艺对双端口谐振器封装后,进一步提升了频率稳定性。低噪声电路由两级放大组成,在提供足够增益的情况下,提升了相位噪声性能。之后测试得到的相位噪声分别是在1 kHz 频偏处为-96 dBc/Hz,噪底 -128 dBc/Hz 。中期稳定性和阿伦方差的测试结果分别为±4 ppm和10 ppb。这些结果均表明,该振荡器在新一代无线通信中有广阔的应用前景。     

双反馈晶振和石英谐振器低噪声性能的进一步研究

本文进一步探讨了有关双反馈晶振低噪声性能的问题,着重分析了石英谐振器静电容C_0对双反馈晶振电路Q倍增固子、石英谐振器Q值及净噪特性的影响。为验证上述C_0的影响,也对不同C_0的石英谱振器的相噪特性进行了测量并得到了与分析一致的结果。     

A Ka-band micromachined low-phase-noise oscillator

A low-phase-noise 28.65 GHz oscillator has been demonstrated using a planar resonator. The resonator is micromachined close to the transistor and has an unloaded Q of 460. The oscillator uses a commercially available high electron mobility transistor (HEMT) for the active device, and results in an output power of 0.6 dBm with a 5.7% DC-RF efficiency. The measured phase noise is -92 dBc/Hz at a 100 kHz offset frequency and -122 dBc/Hz at 1 MHz offset frequency. This is compared with a low-Q planar design showing a 10 dB improvement in phase noise. The micromachined resonator is competitive with other hybrid nonplanar technologies, such as dielectric resonators     

A phase noise reduction technique in microwave oscillator using high-Q active filter

The authors present a 10 GHz oscillator that uses a high-Q active filter to reduce the phase noise. The loaded Q of active filter is obtained at about 500. This oscillator is compared with another oscillator which uses a passive filter. The difference of two oscillators' Q is estimated at 12.5 times the open-loop gain simulation. The measured result of phase noise at 100 kHz offset shows maximum 10 dB reduction with high-Q active filter.     

Oscillator with High Harmonic Suppression Using Split Quarterwave Microstrip Resonator

This letter presents a new type of resonator, namely, the split quarterwave microstrip resonator (SQMR), to improve the poor harmonic suppression and low Q‐factors in conventional quarterwave microstrip resonators. An oscillator incorporating the proposed SQMR is designed, fabricated, and tested to demonstrate that, not only the second harmonic suppression, but also the phase noise of the oscillator can be improved. The oscillator with the SQMR shows improved second harmonic suppression of –74.59 dBc and phase noise figure of merit of –169.77 dBc/Hz at 1 MHz offset.     

Miniaturisation and high quality factor of spiral meander spurline resonator for microwave oscillator

The spiral meander spurline structure is an optimal solution for a reduced resonator size and a high Quality factor (Q-factor) compared to other conventional spurline structures. The spiral meander spurline resonator shows not only 38% reduced dimensional effect, but also 16% improved Q-factor compared with conventional meander spurline resonator. Moreover, in order to get more high quality factor, we analysed spurline slot width variation and designed the symmetric dual spiral meander structure, which has a 46.87% improved Q-factor compare with a single spiral meander. The symmetric dual spiral meander structure resonator performance results are shown in a return loss of ?0.76?dB, an insertion loss of ?46.32?dB, and a quality factor of 235 at 6.4?GHz C-band application. In addition, according to the design and performance of the resonator, we can derive from this performance a low phase noise oscillator. The oscillators using symmetric dual spiral meander structure resonator shows good phase noise performances of ?104.43?dBc/Hz at a 100?kHz offset from the carrier frequencies of 6.38?GHz at output powers of 12.2?dBm, respectively.     

Phase noise in self-injection-locked oscillators - theory and experiment

Phase-noise analysis of the self-injection-locked oscillator is presented in this paper. The analysis is developed for different oscillator models and arbitrary self-injection feedback loops. The results are illustrated with specific cases of simple time-delay cable and a high-Q factor resonator. It is shown that the behavior of the phase noise is similar to an oscillator locked to an external low phase-noise source. The output phase noise can be reduced at the noise offset frequency near the carrier frequency, and returning to the free-running oscillator noise far from the carrier frequency for certain stable feedback delay ranges. The phase-noise reduction is affected by the self-injection signal strength and feedback transfer function for different oscillator equivalent-circuit models. The theory is verified by using a self-injection-locked GaAs MESFET oscillator operating at the X-band with delay cable loops. The self-injection-locked technique may be used to improve the phase noise of the existing oscillators.     

Phase Feedback for Nonlinear MEM Resonators in Oscillator Circuits

In this paper, a phase feedback approach for using nonlinear microelectromechanical (MEM) resonators in oscillator circuits is investigated. Phase feedback makes use of the oscillation phase condition for oscillator circuits and enables fine-tuning of the frequency at which the resonator oscillates by means of setting the phase in the feedback amplifier. The principle of the approach is illustrated for a nonlinear Duffing resonator, which is representative of many types of MEM resonators. Next, the approach is applied to an electrostatically actuated nonlinear clamped–clamped beam MEM resonator, on simulation level. Phase feedback allows for operation of the resonator in its nonlinear regime. The closed-loop technique enables control of both the frequency of oscillation and the output power of the signal. Additionally, optimal operation points for oscillator circuits incorporating a nonlinear resonator can be defined. Application of phase feedback results in more robustness with respect to dynamic pull in than in open-loop case, however, at the cost of a deteriorated phase noise response.      

RF HBT oscillators with low-phase noise and high-power performance utilizing a (/spl lambda//4/spl plusmn//spl delta/) open-stubs resonator

This paper presents a new type of transmission-line resonator and its application to RF (microwave and millimeter-wave) heterojunction bipolar transistor (HBT) oscillators. The resonator is a parallel combination of two open stubs having length of /spl lambda//4/spl plusmn//spl delta/(/spl delta//spl Lt//spl lambda/), where /spl lambda/ is a wavelength at a resonant frequency. The most important feature of this resonator is that the coupling coefficient (/spl beta//sub C/) can be controlled by changing /spl delta/ while maintaining unloaded Q-factor (Q/sub u/) constant. Choosing a small value of /spl delta/ allows us to reduce /spl beta//sub C/ or equivalently to increase loaded Q-factor (Q/sub L/). Since coupling elements such as capacitors or electromagnetic gaps are not needed, /spl beta//sub C/ and Q/sub L/ can be precisely controlled based on mature lithography technology. This feature of the resonator proves useful in reducing phase noise and also in enhancing output power of microwave oscillators. The proposed resonator is applied to 18-GHz and 38-GHz HBT oscillators, leading to the phase noise of -96-dBc/Hz at 100-kHz offset with 10.3-dBm output power (18-GHz oscillator) and -104-dBc/Hz at 1-MHz offset with 11.9 dBm (38-GHz oscillator). These performances are comparable to or better than state-of-the-art values for GaAs- or InP-based planar-circuit fundamental-frequency oscillators at the same frequency bands.     

Low phase noise heterojunction bipolar transistor oscillator

A low phase noise, heterojunction bipolar transistor (HBT) oscillator has been designed and fabricated for operation at X-band. The common emitter oscillator employs a high-Q dielectric resonator as the parallel feedback element between the base and collector terminals. Series capacitive feedback is used in the emitter to enhance the oscillator's negative output impedance. Single-sideband FM noise levels of -76 dBc/Hz and -102 dBc/Hz have been achieved at 1 kHz and 10 kHz frequency offsets, respectively, for an 11.06 GHz carrier frequency. This is one of the lowest phase noise levels ever reported for an X-band solid-state transistor oscillator.<>     

推–推振荡器共用谐振器分析与低相位噪声设计

为实现低相位噪声平面振荡器,对推-推振荡器的共用谐振器与相位噪声优化方法进行了研究。提出一种基于多环式开口谐振环的差分传输线,通过加载一对耦合谐振环的方式实现2个单元振荡器之间的弱耦合,提高了共用谐振器的频率选择特性。基于该结构设计并实现了一种X波段推-推振荡器,在设计中采用一种基于振荡器有源品质因子的相位噪声优化方法。测试结果表明：该振荡器在输出二次谐波9.52 GHz处的相位噪声为-115.48 dBc/Hz@100 kHz,基波抑制度达到-54.55 dBc。     

一种钽酸锂压控振荡器的设计与实现

该文使用具有低电容比、宽调谐范围的钽酸锂晶体设计了一巴特勒共基低相位噪声压控振荡器,此设计在寻求高有载品质因数QL的同时保持了振荡器的输出功率。使用的钽酸锂晶体的无载品质因数Q0约为1.24×103,其频率为10.727MHz。设计出的巴特勒振荡器QL≈33%Q0,输出功率约为11dBm。不加压控的情况下,实际测得该振荡器的相位噪声结果为-85dBc/Hz@10 Hz和-145dBc/Hz@1kHz。在此基础上,增加一变容二极管作为压控元件设计了钽酸锂压控振荡器,在2~10 V范围内,测得控制电压压控斜率约为86.6×10-6/V,相位噪声测试结果优于-82dBc/Hz@10Hz和-142dBc/Hz@1kHz,实现了具有宽调谐范围的低相位噪声钽酸锂振荡器的设计。