Dielectric Resonator Oscillator Research Articles

A Tunable Dielectric Resonator Oscillator with Phase-Locked Loop Stabilization for THz Time Domain Spectroscopy Systems

Precision microwave measurement systems require highly stable oscillators with both excellent long-term and short-term stability. Compared to components used in laboratory instruments, dielectric resonator oscillators (DRO) offer low phase noise with greatly reduced mechanical complexity. To further enhance performance, phase-locked loop (PLL) stabilization can be used to eliminate drift and provide precise frequency control. In this work, the design of a low-cost DRO concept is presented and its performance is evaluated through simulations and measurements. An open-loop phase noise of −107.2 dBc/Hz at 10 kHz offset frequency and 12.8 GHz output frequency is demonstrated. Drift and phase noise are reduced by a PLL, so that a very low jitter of under 29.6 fs is achieved over the entire operating bandwidth.

Microwave wireless power transfer system using a dual-dielectric resonator oscillator

Non-radiating wireless power transfer (WPT) systems have found extensive applications in science and technology. This paper reports the design, simulation, and implementation of a compact single-port (DC to RF) WPT system composed of two coupled dielectric resonators (DR). The DR on the transmitter side, in combination with a transistor amplifier and a series feedback circuit, forms a dielectric resonator oscillator for microwave power generation. The DR on the receiver side is coupled to the transmitter DR such that the circuit can be considered as a dual-dielectric resonator oscillator or DDRO. The DDRO is designed for optimum power transfer to the output port. The measured RF output power of the proposed WPT system at 7.5 GHz for a 10 mm spacing between the transmitting and receiving DR is measured to be 13.07dBm at a DC voltage of 3.3 V and a supply current of 32.3 mA, which shows a good agreement with our proposed method of analysis. The available bandwidth at the operating frequency of 7.5 GHz is measured to be 150 MHz which provide a relatively wide bandwidth for simultaneous data transmission.

Fabrication and characterization of (Mg0.8Zn0.2)(Ti0.99Sn0.01)O3 ceramics as a 4.0 GHz resonator in dielectric resonator oscillator module

Fabrication and characterization of (Mg0.8Zn0.2)(Ti0.99Sn0.01)O3 ceramics as a 4.0 GHz resonator in dielectric resonator oscillator module

A low-noise X-band microwave source with digital automatic frequency control for electron paramagnetic resonance spectroscopy

We report a new design of microwave source for X-band electron paramagnetic resonance spectrometer. The microwave source is equipped with a digital automatic frequency control circuit. The parameters of the digital automatic frequency control circuit can be flexibly configured for different experimental conditions, such as the input powers or the quality factors of the resonator. The configurability makes the microwave source universally compatible and greatly extends its application. To demonstrate the ability of adapting to various experimental conditions, the microwave source is tested by varying the input powers and the quality factors of the resonator. A satisfactory phase noise as low as −135 dBc/Hz at 100-kHz offset from the center frequency is achieved, due to the use of a phase-locked dielectric resonator oscillator and a direct digital synthesizer. Continuous-wave electron paramagnetic resonance experiments are conducted to examine the performance of the microwave source. The outstanding performance shows a prospect of wide applications of the microwave source in numerous fields of science.

All-Polarization-Maintained Microwave Photonic Phase Detector Based on a DP-DMZM

An all-polarization-maintained microwave photonic phase detector (MPPD) based on a dual-polarization dual-drive Mach-Zehnder modulator (DP-DMZM) is demonstrated to detect the phase difference between a microwave signal and an optical pulse train. The robustness of the MPPD can be significantly improved with the all-polarization-maintained structure. A proof-of-concept experiment is carried out. An 8.032-GHz dielectric resonator oscillator (DRO) is locked to an optical pulse train through this MPPD with its phase noise reducing from −109.68 dBc/Hz to −135.41 dBc/Hz at 10-kHz offset frequency. The DP-DMZM-based MPPD shows that the minimum value of the noise floor is around −154 dBc/Hz, and the integrated residual timing jitters from 100 Hz to 100 kHz, 1 MHz, and 3 MHz are 276 as, 696 as, and 2.50 fs, respectively. The MPPD has good stability against external vibrations and stresses.

Synchronization of Two Microwave Sources With Femtosecond-level Residual Timing Jitters Using a Microwave Photonic Phase Detector

A microwave photonic phase detector (MPPD) for simultaneous synchronization of two independent microwave sources to a single mode-locked laser (MLL) with femtosecond-level residual timing jitters is firstly proposed and experimentally demonstrated. A Sagnac loop is built based on a dual-polarization dual-drive Mach-Zehnder modulator (DP-DMZM). Each path consisting a branch of the modulator forms an MPPD due to its feature of polarization multiplexing. Thus, two dielectric resonator oscillators (DROs) can be synchronized simultanesously. A proof-of-concept experiment is carried out. Two independent DROs with frequencies of 8.0320 and 8.3332 GHz are synchronized to an MLL. The phase noises of the synchronized 8.0320-GHz signal are −109.79 and −135.14 dBc/Hz at the 1-kHz and 10-kHz offset frequencies, respectively, and those of the 8.3332-GHz signal are −106.87 and −133.86 dBc/Hz. The residual timing jitters of the two synchronized signals (integrated from 100 Hz to 1 MHz) are around 2.12 fs and 5.93 fs, respectively. The impact of the amplitude and phase imbalances of the driven signals to the DP-DMZM on the performance of the MPPD is investigated.

A Novel architecture for low-jitter multi-GHz frequency synthesis

Abstract A phase-locked loop (PLL) cascade driven by a crystal oscillator and a free running dielectric resonator oscillator (DRO) is proposed. For minimizing phase noise, spurious tones and jitter, a programmable PLL1 in the lower GHz range is used to drive a millimeter-wave (mmW) PLL2 with a fixed frequency multiplication factor. The phase noise analysis results in two optimum bandwidths of the two PLLs for the lowest output jitter of the cascade. Phase noise and spurious tones (spurs) in PLL1 are further reduced by dividing the output frequency of PLL1 and up-converting it by means of a single-sideband (SSB) mixer driven by the DRO. By including the SSB mixer in the feedback loop of PLL1 manual tuning of the DRO is avoided, and a low-noise free running DRO can be employed. An exemplary design in SiGe BiCMOS technology is presented.

Investigation of Dielectric Resonator Oscillator Using High-Electron Mobility Transistor at 26GHz for Space Applications

An oscillator is a vital component as the energy source in microwave telecommunication system. Microwave oscillators designed using Gunn diode have poor DC to RF efficiency. IMPact Ionization Avalanche Transit-Time diode (IMPATT) oscillators have the drawback of poor noise performance. The transistorized oscillators have a limitation to the maximum oscillation frequency which means that they cannot be used for oscillators designed for high frequencies. To design negative series feedback Dielectric Resonator Oscillator (DRO), the resonant unit uses a dielectric resonator (DR) since it is small in size, light in weight, has high-Quality ([Formula: see text]) factor, better stability and also it is inexpensive. It has the benefits of low-phase noise, low cost, miniaturization, high stability, applicable for devices designed at high frequencies and had already been widely applied, so the research on microwave dielectric oscillator has also been one of the focus of today’s microwave integrated circuits. DRO is widely used in electronic warfare, missile, radar and communication systems. The DRO incorporates High-Electron Mobility Transistor (HEMT) as an active device since it offers higher power-added efficiency combined with excellent low-noise figures and performance. The entire circuit of DRO using HEMT at 26[Formula: see text]GHz is designed using Agilent Advanced Design System (ADS) software. In this, DRO different measurements of parameters are done such as output power which is typically [Formula: see text][Formula: see text]dBm for 26[Formula: see text]GHz DRO, phase noise at 10[Formula: see text]kHz offset for 26[Formula: see text]GHz DRO it is 80[Formula: see text]dBc/Hz. The frequency pushing and frequency pulling for 26[Formula: see text]GHz DRO its typical values are 30[Formula: see text]kHz/V and 1[Formula: see text]MHz, respectively.

THE USE OF (Mg0.9Zn0.1)TiO3+2wt.% Bi2O3 CERAMICS AS A DIELECTRIC RESONATOR OSCILLATOR MATERIAL AND CHARACTERISATION OF STRUCTURE, MICROSTRUCTURE, AND DENSITY

Magnesium titanate (MgTiO3)-based ceramics have the potential for use in the telecommunications industry at microwave frequencies, including as a resonator in dielectric resonator oscillator (DRO) circuit. This research is intended to study the application of (Mg0.9Z0.1)TiO3+2wt.% Bi2O3 (abbreviated MZT01-2) ceramics as DRO material and characterize the structure, microstructure, and bulk density. Fabrication was carried out by ball milling between (Mg0.9Z0.1)TiO3 crystalline powder and 2wt.% Bi2O3 powder. The milled powder was compacted at certain pressure using a die press to become pellets. All pellets were sintered at 1000, 1100, 1200°C for 4 h to obtain ceramics. The structural characterization using XRD showed that the three ceramics contained the main MgTiO3 phase, each 93.63, 93.83, and 90.78% molar, the rest was the MgTi2O5 phase. The increase in sinter temperature causes the lattice parameter and the unit cell volume to decrease. The Archimedes bulk density was 2.928; 2.832 and 2.736 g/cm3. The microstructure is solid surfaces with a grain diameter of 1.9-2.3 μm accompanied by pores. As DRO materials, the three ceramics exhibited a resonant frequency at 5.11, 5.08, and 5.12 GHz which shows that the ceramics can be applied as DRO materials at microwave frequencies. The sinter temperature variation tends not to affect the resonant frequency position.

Characterization of (Mg1.0Zn0.0)TiO3+4 wt%Bi2O3 Ceramics for Application as Resonator in Dielectric Resonator Oscillator Circuit

MgTiO3-based ceramics have potential applications in telecommunications systems at microwave frequencies, such as resonators in dielectric resonator oscillator (DRO) circuits. This paper reports the results of (Mg1.0Zn0.0)TiO3+4wt% Bi2O3 (abbreviated MZT0+4wt%Bi2O3) ceramic fabrication to assess its potential to be used as a resonator in the DRO circuit. We characterized its structure, microstructure, and bulk density. The addition of 4wt%Bi2O3 to MZT0 crystalline powder was carried out via ball-mill. The milled powder was compacted using a die press to obtain pellets. All pellets were sintered at 1100ºC for 4, 6, and 8 h. Ceramic structures of the 4 and 6 h holding time consists of MgTiO3 phase (94.33±2.68) and (95.34±1.95)% molar respectively, while the rest phase was TiO2. The 8-h ceramic structure comprises (96.11±2.94) % molar MgTiO3 accompanied by Mg2TiO5 and TiO2. The ceramics' microstructure consists of a cluster of grains with an average diameter of 1.32-2.24 μm and pores. Bulk density decreases with the increase of sintering holding time. The DRO characterization records a resonance signal each at 5.207, 5.005, and 5.121GHz with power approaching 0 dBm, suggesting that the MZT0+4wt%Bi2O3 ceramics can be used as a resonator in the DRO circuit working in microwave frequencies, especially at 5.0-5.2GHz.

The Response of (Mg0.6Zn0.4)TiO3 Ceramic System as A Dielectric Resonator Oscillator at C-Band

Magnesium titanate (MgTiO3) with the ilmenite structure has been recognized as a potential dielectric ceramic material for modern cellular technology, satellite communications in the microwave frequency region, radar systems, filters, resonators and antennas in global positioning systems. This paper demonstrates the response of magnesium zinc titanate (Mg0.6Zn0.4)TiO3 ceramic system when it was mounted as a dielectric resonator element in a dielectric resonator oscillator (DRO) circuit when the circuit was tuned in a transverse electric (TE)01δ resonant mode operating at the frequency range of 3 – 12 GHz. The discussion is related to the structure, microstructure and dielectric characteristics.

Highly stable signal generation in microwave interferometer using PLLs

Abstract The microwave interferometer is a device that works in the millimeter-wave frequency range, and it is used to measure the plasma density. The instability in the frequency source at the transmitter section of the interferometer affects the accuracy of the phase measurement in the receiver section. The phase-locked loop (PLL) circuit is a substantial unit in the generation of highly stable frequency. This paper proposes a highly stable frequency source generator for the D-band Microwave interferometer. The design, development, and analysis of the PLL system with the frequency signal of 6.9 GHz and 7.0 is presented in this paper. Two alternate approaches using the dielectric resonator oscillator (DRO) and Frequency synthesizer are presented to design the PLL circuit. The stability is achieved using a 7 GHz DRO in the transmitter section, which is phase-locked with a 6.9 GHz voltage controlled oscillator (VCO) at the receiver section in the proposed first design and a frequency synthesizer is used instead of DRO in the proposed second design. The developed circuit is analysed in terms of parameters like phase noise performance, output power level, development cost, design complexity, and operating frequency range. The PLL in the receiver section is configured using FPGA to analyze the circuit performance at various frequency offset. DRO generates the power of 17.62 dB m at a frequency of 7.0 GHz. The DRO and synthesizer circuit provides excellent phase noise performance of -120 dBc/Hz and -93 dBc/Hz, respectively, at the transmitter section and -94.12 dBc/Hz at the receiver section. Indigenous methods have been made for the development of PLLs. It will be used to develop a D-band microwave interferometer to measure the electron density of fusion plasma at the Institute for plasma research (IPR)-Government of India.

300 GHz wave generation based on a Kerr microresonator frequency comb stabilized to a low noise microwave reference.

In this Letter, we experimentally demonstrate low noise 300 GHz wave generation based on a Kerr microresonator frequency comb operating in the soliton regime. The spectral purity of a 10 GHz GPS-disciplined dielectric resonant oscillator is transferred to the 300 GHz repetition rate frequency of the soliton comb through an optoelectronic phase-locked loop. Two adjacent comb lines beat on a uni-traveling carrier photodiode emitting the 300 GHz millimeter-wave signal into a waveguide. In an out-of-loop measurement, we measure the 300 GHz power spectral density of phase noise to be -88dBc/Hz, -105dBc/Hz at 10 kHz, and 1 MHz Fourier frequency, respectively. Phase-locking error instability reaches 2×10-15 at 1 s averaging time. Such a system provides a promising path to the realization of compact, low power consumption millimeter-wave oscillators with low noise performance for out-of-the-laboratory applications.

Single transistor low phase noise active dielectric resonator oscillator

AbstractIn this paper, the design theory of an 8 GHz oscillator with a new structure of active dielectric resonator (DR) is presented. The new structure emphasizes on phase noise reduction by using only one active device. The proposed structure uses additional feedback from transistor to resonator in order to increase the quality factor. Measurement results report that phase noise is reduced to −145.19 dBc/Hz at 100 kHz offset frequency which represents 12 dB improvement compared with oscillators with passive DR. Also, in comparison with conventional active resonator oscillators, noise source of the second amplifier which makes spurious oscillation is removed. The size and power consumption are reduced due to the use of a single transistor. This structure has the lowest phase noise in comparison with other DR oscillators. In order to implement the proposed oscillator, a circuit including amplifier, resonator, coupler, and phase shifter is designed and realized.

Demonstration of a Sub-Sampling Phase Lock Loop Based Microwave Source for Reducing Dick Effect in Atomic Clocks**Supported by the National Key Research and Development Program of China under Grant No 2017YFA0304400, and the National Natural Science Foundation of China under Grant Nos 91336213, 11703031, U1731132 and 11774108.

We demonstrate a simple scheme of 6.835 GHz microwave source based on the sub-sampling phase lock loop (PLL). A dielectric resonant oscillator of 6.8 GHz is directly phase locked to an ultra-low phase noise 100 MHz oven controlled crystal oscillator (OCXO) utilizing the sub-sampling PLL. Then the 6.8 GHz is mixed with 35 MHz from an direct digital synthesizer (DDS) which is also referenced to the 100 MHZ OCXO to generate the final 6.835 GHz signal. Benefiting from the sub-sampling PLL, the processes of frequency multiplication, which are usually necessary in the development of a microwave source, are greatly simplified. The architecture of the microwave source is pretty simple. Correspondingly, its power consumption and cost are low. The absolute phase noises of the 6.835 GHz output signal are −47 dBc/Hz, −77 dBc/Hz, −104 dBc/Hz and −121 dBc/Hz at 1 Hz, 10 Hz, 100 Hz and 1 kHz offset frequencies, respectively. The frequency stability limited by the phase noise through the Dick effect is theoretically estimated to be better than 5.0 × 10−14τ1/2 when it is used as the local oscillator of the Rb atomic clocks. This low phase noise microwave source can also be used in other experiments of precision measurement physics.

Compact Phase Detector for Optical-Microwave Synchronization Using Polarization Modulation

We propose and demonstrate a compact optical-microwave phase detector taking advantage of polarization modulation. The proposed polarization modulator-based phase detector (PolM-PD) shows 460-attosecond residual timing jitter integrated from 1 Hz to 100 kHz when synchronizing an 8-GHz dielectric resonator oscillator to a free-running 250-MHz mode-locked Er-fiber laser. The absolute single-sideband phase noise of the locked 8-GHz DRO is –138 dBc/Hz (–165 dBc/Hz) at an offset frequency of 10 kHz (10 MHz). The proposed PolM-PD has a compact structure implemented by all commercially available components. Because no fiber loop and delay line are used, the proposed PolM-PD can be potentially integrated on a chip.

Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR).

We report on the development of two 874 GHz receiver channels with orthogonal polarizations for the International Submillimetre Airborne Radiometer. A spline horn antenna and dielectric lens, a Schottky diode mixer circuit, and an intermediate frequency (IF) low noise amplifier circuit were integrated in the same metallic split block housing. This resulted in a receiver mean double sideband (DSB) noise temperature of 3300 K (minimum 2770 K, maximum 3400 K), achieved at an operation temperature of 40 °C and across a 10 GHz wide IF band. A minimum DSB noise temperature of 2260 K at 20 °C was measured without the lens. Three different dielectric lens materials were tested and compared with respect to the radiation pattern and noise temperature. All three lenses were compliant in terms of radiation pattern, but one of the materials led to a reduction in noise temperature of approximately 200 K compared to the others. The loss in this lens was estimated to be 0.42 dB. The local oscillator chains have a power consumption of 24 W and consist of custom-designed Schottky diode quadruplers (5% power efficiency in operation, 8%-9% peak), commercial heterostructure barrier varactor (HBV) triplers, and power amplifiers that are pumped by using a common dielectric resonator oscillator at 36.43 GHz. Measurements of the radiation pattern showed a symmetric main beam lobe with full width half maximum <5° and side lobe levels below -20 dB. Return loss of a prototype of the spline horn and lens was measured using a network analyzer and frequency extenders to 750-1100 GHz. Time-domain analysis of the reflection coefficients shows that the reflections are below -25 dB and are dominated by the external waveguide interface.

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.

New Configuration of a PLDRO with an Interconnected Dual PLL Structure for K-Band Application

A phase-locked dielectric resonator oscillator (PLDRO) is an essential component of millimeter-wave communication, in which phase noise is critical for satisfactory performance. The general structure of a PLDRO typically includes a dual loop of digital phase-locked loop (PLL) and analog PLL. A dual-loop PLDRO structure is generally used. The digital PLL generates an internal voltage controlled crystal oscillator (VCXO) frequency locked to an external reference frequency, and the analog PLL loop generates a DRO frequency locked to an internal VCXO frequency. A dual loop is used to ease the phase-locked frequency by using an internal VCXO. However, some of the output frequencies in each PLL structure worsen the phase noise because of the N divider ratio increase in the digital phase-locked loop integrated circuit. This study examines the design aspects of an interconnected PLL structure. In the proposed structure, the voltage tuning; which uses a varactor diode for the phase tracking of VCXO to match with the external reference) port of the VCXO in the digital PLL is controlled by one output port of the frequency divider in the analog PLL. We compare the proposed scheme with a typical PLDRO in terms of phase noise to show that the proposed structure has no performance degradation.

Limits in Timing Jitters of Forced Microwave Oscillator Using Optical Self-ILPLL

A novel optical feedback technique using self-injection locked and phase locked loop (SILPLL) is employed for phase noise reduction of free-running microwave oscillators. Phase noise reduction of 27 dB at 10-kHz offset has been demonstrated by applying this technique for a 10-GHz state of art dielectric resonator oscillator achieving −137 dBc/Hz at 10-kHz offset. A phase noise prediction of this feedback technique is also presented, which very closely corroborates with experimental results. Analysis of SILPLL using the modeling has shown that further phase noise reductions could be achieved, by reducing the flicker phase noise of the long delay lines and microwave amplifiers. Phase noise of −147 dBc/Hz at 10-kHz offset is predicted when the relative intensity noise (RIN) is reduced to the RIN of −170 dB/Hz for an optical power leading to a photocurrent of 5 mA and the $\text{b}_{\mathrm {\mathbf {-1}}}$ (flicker noise) levels of −125 dBc/Hz for RF amplifiers.