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This paper describes the design and performance of four Ku-band common-source dielectric resonator oscillators (DROs). The first uses open-circuited stubs at the source to create instability, while the second employs an additional dielectric resonator (DR) for the same purpose. The third has the source connected to a 50Omega impedance and the fourth has the source grounded. A comparison is made between the general characteristics of the four configurations.

A new type of highly stabilized GaAs FET oscillator using a dielectric resonator and a stabilized resistor in the feedback circuit has been developed. The oscillator fabricated with a microwave integrated circuit has a high external quality factor. Dielectric-resonator oscillators (DROs) offer such advantages as good frequency stability, the possibility of tuning with varactors, and simple, low-cost construction. A DOR design method is available that combines accuracy and simplicity as it requires only small-signal parameters (which are typically available from manufacturers). The microwave characteristics of the GaAs FET oscillator have revealed: 1) High efficiency of 20 percent output power at 10 GHz, 2) a wide tuning range more than 1000 MHz, 3) a wide oscillation frequency from 9 to 14 GHz with same MIC pattern by using five dielectric resonators of different sizes, 4) a high-frequency stability as low as 150 kHz in the temperature range from -20 to +60 /spl deg/C.

This paper describes the design of very low noise, tunable, X band dielectric resonator oscillators (DROs) demonstrating phase noise performance of -135 dBc/Hz at 10 kHz offset. A variety of resonator configurations utilising BaTiO/sub 3/ resonators are presented demonstrating unloaded Qs from 10,000 to 30,000. These resonators are optimally coupled to the amplifiers for minimum phase noise where Q/sub L//Q/sub 0/= 1/2 and S/sub 21/=-6 dB. SiGe transistors are used for the oscillator sustaining amplifiers which offer reasonable levels of circulating power /spl sim/15 dBm and gains of 5.4 dB per stage as well as low flicker noise corners between 10 and 40 kHz. To incorporate tuning, with low additional phase noise, phase shift tuning is incorporated. The theory for the design is included demonstrating close correlation with experimental results.

A pulsed priming technique has been applied to series feedback DROs (dielectric resonator oscillators). Using the method, a DRO electrically tuned over 0.4% started in 60 ns without observable starting time jitter, settled to with +or-10 ppm in 150 ns, and delivered an output power of 14 dBm with a phase noise level of -92 dBc/Hz. A fixed tuned DRO also showed over 700-ns improvement in starting time when pulse primed with a phase noise level of -95 dBc/Hz. Since resonator Q reduction is not required, the inherent oscillator phase noise is not degraded. The present technique of introducing the priming signal allows for electrical tuning of the oscillator. >

MESFET dielectric resonator oscillators (DROs) have been demonstrated at V-band. The first unit operates at 51.2 GHz with an output power as high as 9 dBm. The second unit operates at 65.6 GHz with an output power of 7.6 dBm. DC-to-RF efficiencies were 18% and 14%, respectively. Power variation is less than +or-0.25 dB over a temperature range from 0 to 50 degrees C. The stable output power over temperature makes this FET oscillator more attractive than its diode counterpart. The planar circuit structure employed in this oscillator can be implemented monolithically. >

This paper presents a novel way of designing a dielectric-resonator VCO with a great stability, high output frequency, and more important, in a cheap way using CAD. In this new way of design, a parallel half wave transmissions line is coupled with a dielectric resonator and two varactors that are used to change the frequency of oscillation. The oscillation frequency is tuned on 11 GHz with /spl plusmn/4 MHz tolerance. The varactor diodes play a crucial role in this circuit; the capacitance of the diodes change as the voltage changes, so this changing in capacitance results in a change in the length of the transmission line; consequently, the output frequency of the circuit alters; in this way we have an oscillator. One of the eminent applications for this configuration is phase-locked DRO. This DRVCO was implemented and tested successfully.

A novel analysis of a DRO in which the temperature stability is related to that of the DR cavity and the thermal variation of active device large signal admittance is presented. This serves as design tool for optimally stable DROs where a tradeoff can be struck between output power and temperature stability. A simpler design technique is also described which relies on the measurement of a DRO circuit with a known DR temperature coefficient A theoretical method for the prediction of the temperature stability of a DR is also presented and is shown to compare very well with experimental results. A fully automated load-pull system bas also been developed for the large signal characterisation of active devices and results are given for a medium power TED.

Microwave dielectric oscillation frequency source uses a small size, light weight, high Q value, inexpensive dielectric resonator (DR) as a resonant unit. It has the advantages of miniaturization, low phase noise, high stability and low cost and had already been widely applied, so the research on microwave dielectric oscillator has also become one of the focus of today's microwave integrated circuits. [1] This paper describes the working principle and design method of the DRO. Through reading lots of literature on DROs, the author has deeply knows about the theory of DROs and designs a circuit with both HFSS and ADS simulation software.

Microwave dielectric resonator oscillators (DRO) offer high performance in a small footprint. Phase locked DROs are essential components in microwave links, where phase noise is a critical parameter. A novel circuit topology is presented, applicable to fixed frequency, voltage controlled DROs, which results in improved phase noise performance. The theory behind the approach is presented along with the results achieved from the design produced by EADS Astrium, as part of a flight program.

We report on the design, fabrication, and RF performances of 24-27 GHz dielectric resonator oscillators (DROs) using InP/InGaAs HBTs. The employed HBT devices yield f/sub T/ values of 70 GHz and f/sub max/ values of up to 180 GHz, respectively. The measured phase noise of -107 dBc at 100 kHz offset is significantly lower than that of comparable DROs using GaAs based HBTs. To our knowledge, this is the first demonstration of phase noise results on InP/InGaAs HBT DROs.

Two design methods are presented which result in a simple, low-cost and highly stable L-band VCO. One method uses microwave transistors and a high dielectric constant microstrip line which couples with DR. The frequency tuning range of the oscillator is more than 0.5% using this method. The other design method is based on the C-band Self-Oscillation Mixer (SOM) since the L-band DR is too large to use on the one hand. On the other hand, the Q-factor of the DR with the relative dielectric constant of 80 is much lower than that in normal use. The C-band DR is found to be suitable in this case. The L-band VCO consists of two C-band DROs. The L-band output frequency is the frequency difference of the two DROs. This design has the advantages of good frequency stability and relatively large tuning range (2%). >

A new Spacecraft Transponding Modem (STM) is being developed for deep space communication applications. The STM receives an X-band (7.17 GHz) uplink signal and generates an X-band (8.4 GHz) and a Ka-band (32.0 GHz) coherent or noncoherent downlink signals. The STM architecture incorporates three miniature dielectric-resonator-oscillators (DRO). These DROs are used in receiver and exciter frequency synthesis phase-locked loops (PLL) in the STM. The DROs are designed with custom developed monolithic microwave integrated circuit (MMIC) negative resistance oscillator chips. DROs are laid out on alumina substrates in RF cavity fixtures of 18 mm/spl times/18 mm/spl times/8 mm. The receiver and the exciter DRO designs meet the following requirements: frequency stability of /spl plusmn/2 ppm//spl deg/C, the free running single-sideband phase noise of -50 dBc at 1-kHz offset frequency, tuning linearity of /spl plusmn/10% over the /spl plusmn/1.75-MHz locking range, and output power of +10 dBm/spl plusmn/1 dB over a design temperature range of -55/spl deg/C to +85/spl deg/C. The phase-locked loop DRO frequency synthesizers are designed using sampling downconverter and phase detector MMIC chips. These PLL frequency synthesizers meet the following requirements: pull-in range of /spl plusmn/1.75 MHz, loop noise bandwidth of 100 kHz, and a single-sideband phase noise of -144 dBc at 1-kHz offset frequency.

Summary form only given. Doubly-resonant OPOs (DROs) are attractive for their low thresholds. This is especially important in the case of diode-laser pumping where available power is usually limited and further reductions in threshold are often made by the use of quasi-phase-matched materials such as PPLN. We have carried out an analysis which attributes this behavior to several clusters falling within the phase-matching bandwidth of the material and therefore having similar thresholds. The results of our study indicate that a phase-matching bandwidth much larger than the cluster spacing is common to many demonstrated, or potential, QPM materials pumped at near-infrared wavelengths due to their largely similar dispersive properties The results of our analysis are presented and the implications for diode-pumped DROs using QPM materials, and potential solutions to the problem, are discussed.

Monolithic HFET dielectrically stabilized oscillators (DROs) are designed based on results obtained, from hybrid HFET DROs /1,2/. The monolithic chips are fabricated using MBE grown 2? substrates. The employed low noise quarter micron InGaAs/GaAs pseudomorphic (PM) HFET devices yield fT and fmax values of the least 70 GHz and 140 GHz. State. of-the-art topology DROs show an output power of +11 dBm and +2.3 dBm. at 36 GHz and 62 GHz, respectively. Excellent phase noise data of ?97 dBc/Hz at 100 kHz off carrier (Ka-band DRO) and ?101 dBc/Hz at 1 MHz off carrier (V-band DRO) are obtained.

Existing works on generating random bits by ring oscillators (ROs) mostly do not have detailed analysis on phase noise and jitter which are the entropy source of a random number generator. This paper analyzes the suitability of existing ROs for random number generation and possible improvements in order to increase the randomness of a RO. Randomness equations are derived, to understand efficiency of these derivations, hand calculation and simulation results are compared. For this purpose, two cases are studied: Inverter-based Ring Oscillators (IbRO) and Differential Ring Oscillators (DROs). 0.35µm standard CMOS process has been used with a supply voltage of 3.3V for designs and analysis. For both ROs, randomness increases with decreasing energy. It is also observed that randomness of DRO does not have dependence on V DD as strong as in IbRO. Furthermore, for a given oscillation frequency, DRO exhibits 48 times more randomness than inverter-based one. Therefore, for random number applications, DRO is more suitable in terms of randomness that they produce.

Combining a femtosecond laser optical frequency comb (OFC) with the high quality factor (Q) available in optical cavities allows for the realization of microwave signals with phase noise properties surpassing state-of-the-art microwave oscillators. Optical Fabry-Perot (FP) resonators can have Q values exceeding 1011, much greater than room temperature microwave dielectric resonator oscillators (DRO) at ∼105, and even exceeding that of cryogenic DROs at ∼109. When an optical frequency comb is phase locked to an optical reference, the comb can be thought of as a high fidelity frequency divider, transferring the stability of the optical reference to the microwave domain [1–3]. With this division in frequency comes a division in phase noise, thus an optical reference with a fractional frequency stability of ∼4·10−16 (and assuming flicker FM) can ideally generate a 10 GHz signal with phase noise of ∼−110 f−3 dBc/Hz. At 1 Hz offset from the carrier, this represents a 40 dB improvement over the best room temperature 10 GHz microwave oscillators [4], and is below what has been demonstrated with cryogenic 10 GHz oscillators [5]. Work with Er:fiber-based frequency combs has shown a residual phase noise in optical-to-microwave conversion ∼−118 dBc/Hz at 1 Hz offset from a 11.55 GHz carrier [2]. Recently, we demonstrated absolute phase noise below −104 dBc/Hz at 1 Hz offset from a 10 GHz carrier by comparing two independent systems that employ 1 GHz mode-locked Ti:sapphire laser combs [3]. To our knowledge, this represents the lowest close-to-carrier phase noise yet reported on a 10 GHz source. A schematic of the microwave generation architecture is shown in Fig. 1(a) and data are presented in Fig. 1(b).

SOC has been a familiar concept in hardware design of embedded control systems. There are various evolutions of SOC, such as CSOC, RSOC or USOC. Dynamically reconfigurable SOC (DRSOC) is a new evolution of SOCs. It means the SOC hardware can be modified in operation, but not to shut down power and not to change ex-behaviour. The idea is significant for some fields, such as space developments, intelligent moving systems, military applications and some industrial systems. This paper is focus to discuss the organization of SOCs, updating contents of RSOC/USOC, concept and structure of a DRSOC based on PLD, and to issue a scheme of DROS based on two SOC and one monitor.

This paper describes the developing status of millimeter wave tubes in China. These tubes include magnetrons, klystrons, traveling wave tubes (TWTs), the extended interaction oscillators (ElOs), the extended interaction amplifiers (ElAs), the diffraction radiation oscillators (DROs or orotrons) and gyrotrons. The basic research, such as new types of slow wave structures and fast wave interaction models, is also described. The further developing trends of millimeter wave tubes in China are discussed in this paper.

The creation of diffraction radiation oscillator (DRO) type devices is concerned with the search for novel regimes and excitation conditions of diffraction radiation (DR) electromagnetic oscillations in open electrodynamic structures. The actuality here is the study of radiation directional diagram (DD) changes and other DR features when static and dynamic electron beam parameters are varied (DR fine structure). It is topical, for DROs, to study the radiation fine structure of the electron beam (EB) which interacts with a DRO open resonator field. The dominant task here is the determination of the fine structure of the radiation DD of an EB, incident on a reflecting grating, that interacts with the electromagnetic field.

Methods for improving a diffraction radiation oscillator's (DRO) output characteristics and for the creation of optimal conditions of electron beam/radiation field interaction are of scientific and practical interest. One example of such a study is the determination of the influence of the focusing magnetostatic field (FMF) in the interaction space of a thick electron beam (EB) with an open resonator electromagnetic field. The FMF profiling effect on the quality of microwave signal spectra is insufficiently studied. In this trend, are required additional investigations of the fine structure of the transformation mechanism of electron beam energy into electromagnetic oscillations in designed DROs, taking into account features of FMF change in the interaction space. The key problem, investigated in this paper, is the determination of the degree of influence of IMF inhomogeneity distribution between the pole pieces in the EB motion direction on oscillation excitement processes.

This paper reports on a low phase noise 18 GHz-band HBT oscillator employing a newly proposed transmission line resonator. The phase noise of -96 dBc/Hz at 100 kHz offset achieved is believed to be the best performance reported for HBT oscillators and comparable to that of FET DROs at the same frequency band.

We propose a large signal model for a packaged SiGe heterojunction bipolar transistor. Pulsed I-V measurements are used to avoid thermal effects. The current model yields excellent correlation with pulsed output characteristics and S-parameters up to 18 GHz. The model's validity is established by designing ultra low phase noise C and X band dielectric resonator oscillators (DROs).

In this paper, a technology for the fabrication of high performance InP-based HEMTs using dry gate recess etching is reported. The dry etched devices show better uniformity and considerably reduced low-frequency noise compared to conventionally wet etched ones. As an application of the technology, a dielectric resonator oscillator (DRO) operating in the frequency range of 23.2-24.8 GHz was designed and fabricated using dry or wet etched InGaAs-InAlAs-InP HEMTs. An output power of 12 dBm and a phase noise of -107 dBc/Hz at 100 kHz offset from the carrier were measured for DROs with dry etched HEMTs. These values were superior by nearly 10 dB to those obtained with conventionally wet etched devices. The reduction in phase noise is attributed to hydrogen trap passivation during dry gate recess etching with a methane/hydrogen plasma.

A design procedure for a reflection-stabilized dielectric resonator oscillator (DRO) is given that takes advantage of the facilities available from most linear microwave CAD (computer-aided design) programs, hence streamlining and simplifying the task. The method was used to design 27.61-GHz MESFET hybrid DROs with an average output power of +3 dBm, +or-2-MHz stability from -20 to +40 degrees C, and -75 dBc/Hz phase noise at 10 kHz from carrier. The circuit has been designed to be transferable to GaAs with few modifications. >

Experiments were performed on L-band and S-band dielectric resonators (DRs) and direct-resonator-based oscillators (DROs) to investigate the details of their behavior with variation in temperature. Measurements were performed using commercially available Zr/Sn titanate and barium tetratitanate dielectric resonator materials enclosed in metal cavities. The results indicate that the temperature coefficient of the resonant frequency, tau /sub f/, supplied by vendors of the high-dielectric-constant ceramics, is not sufficient to predict accurately a DRO's total frequency excursion over a given temperature range. Significant second-order contributions to the frequency versus temperature characteristics were observed, with values ranging from -27 to +20 p.p.b./ degrees C/sup 2/. In addition the cavity material used to enclose the DR can significantly alter its temperature characteristic. Procedures have been developed to aid in the estimation of a DRO's characteristic temperature sensitivity. They can be used to adjust the DRO design to minimize the total frequency excursion over a desired temperature range. >

Harmonic dielectric resonator oscillators (HDROs) designed for 25 and 27 GHz were fabricated using a two-stage GaAs MESFET amplifier and a passive two-port resonant structure (RS). The RS consists of a metal cavity, an X-band ceramic dielectric resonator, 50 /spl Omega/ microstrip transmission lines, and a support for elevating the dielectric resonator inside the cavity. The electromagnetic behavior of the RS was analyzed using Hewlett-Packard's High Frequency Structure Simulator (HFSS). The simulator was used to calculate the electromagnetic fields and S-parameters of the passive RS. Solutions were obtained for the dominant mode. The predicted computer results were then compared to measured data. The material properties of dielectric resonators were obtained from two different vendors and evaluated for low-noise microwave oscillator applications. The important material properties for oscillator applications are the unloaded Q, the temperature coefficient, and the dielectric constant. Measured data for resonators from both vendors are presented. The measured phase noise levels at 27 GHz are a 15-20 dBc/Hz improvement over previously published results for DROs. The oscillator also demonstrated a superior frequency vs. temperature characteristic, over the temperature range /spl plusmn/55/spl deg/C, of less than 40 ppm. >

Summary for only given. A number of microwave plasma diagnostic techniques working in the short part of the millimeter wave band require high stability sources with output power about 0.5-1 Watt and the high resolution receiving system. New opportunities for the collective scattering and interferometry can provide a new type of electrovacuum device-Diffraction Radiation Oscillators (DRO) and locked measuring systems based on the DROs. The high stability Vector Analyzer of the superheterodyne type with coherent heterodyning was developed and investigated in a short part of the mm band. The source of the band is the DRO locked in by PLL-system with frequency standard. That allowed increase of the long-time instability up to 5/spl times/10/sub -10/.

In an attempt to better understand the noise performance of a state-of-the-art two-stage L-band dielectric resonator oscillator (DRO), a single-stage DRO was constructed for comparison. The results of this investigation are presented. The discussion begins with a brief analysis of the design and temperature performance of the one- and two-stage DROs. The residual and absolute phase noise performance are discussed. The measured data demonstrate the low phase noise capability and excellent frequency stability of the two-stage, 2-GHz DRO. >

A 38 GHz monolithic DRO (dielectric resonator oscillator) incorporating a 0.3 micron HEMT (high electron mobility transistor) has been designed using a small-signal design procedure. Ten DROs have been tested, seven of which were found to be fully working at RF and gave output powers up to 0 dBm. The temperature coefficient of the frequency of oscillation was -2.1 ppm/ degrees C and the phase noise was -68 dBc/Hz at 100 kHz from carrier. The DRO is potentially inexpensive when produced in high volume and is suitable for a local oscillator in a broadband telecommunications system. >

A state-of-the-art, 8-18-GHz front end comprising four-phase and amplitude-matched frequency converters consisting of ten selectable 1-GHz-wide subband channels has been developed. An integrated local oscillator (LO) distribution module consisting of fine dielectric resonator oscillators (DROs) operating at 11, 12, 13, 14, and 15 GHz provides the downconversion of the 8-18-GHz RF spectrum to a 2-3-GHz intermediate frequency range. The input noise figure of each converter module is 10 dB, with an associated gain of 46 dB+or-1 dB. The spurious-free dynamic range is greater than 47 dB. The DRO oscillator accuracy is +or-5 p.p.m./ degrees C over a temperature range of 0 degrees C to 50 degrees C. The downconverter utilizes a combination of microwave IC (MIC) and monolithic microwave IC (MMIC) components to obtain state-of-the-art performance in a small volume of 1966 cm/sup 3/. >

In this paper we present the design and performance of a K band DRO (Dielectric Resonator Oscillator). The design incorporates NE71000 MESFET and an open source oscillator topology, which we show to be superior in terms of bandwidth and noise. The same circuit can be used (with different resonators) in the frequency range 21-25 GHz. The output power is 10 dbm, frequency stability 4 ppm/degree C and phase noise -88 dbc/Hz@10 kHz (several db better compared to previously published DROs at this frequency range).

Developing the high-stability vector analyzer of superheterodyne type with coherent heterodyning, having high resolution, allows one to measure the amplitude and phase characteristics of objects with a high degree of accuracy. The radiation source of millimetre electromagnetic waves is the diffraction radiation oscillator (DRO). DROs have high frequency stability (10/sup -7/), small parasitic deviation and low level of phase noise. The small-packaged DRO in frequency a range 30-250 GHz with output power of 0.5-50 Wt as a probing source of radiation allows one to investigate substances and devices with large losses in the millimetre wave range. For achievement of a DRO long-term frequency stability compared with the frequency quartz standards, additional adequate conditions are required. With this purpose the experimental research on increase of frequency stability of 4-mm DRO with PLL was carried out.

In millimeter-wave backward-wave oscillators (BWO) and diffraction oscillators (DRO), the frequency instability near the carrier is stipulated by additive noise and modulation noises. In this paper, a model of the fluctuation spectrum of high-frequency oscillation BWOs and DROs near the carrier frequency was constructed. This model allows estimation of the qualitative influence of exterior additive and multiplicate noises on the oscillation frequency of resonant generators in the millimeter wave range and leads to extrapolation of experimental curves in a range of frequencies /spl omega//sub /spl alpha//

Summary form only given. Single-mode diode lasers are attractive pump sources for CW-OPOs due to their compact size, tunability and efficiency. In spite of their relatively low output powers, the availability of quasi-phase-matched materials such as PPLN has enabled the demonstration of practical OPOs pumped by such diode lasers and having thresholds as low as 16 mW. However, simple Fabry-Perot diode lasers typically exhibit poor frequency stability which limits the usefulness of diode-pumped OPOs as stable sources for applications such as spectroscopy. The use of external grating feedback to stabilise diode lasers is a well established technique. Although external cavity operation generally reduces the power available from diode lasers, the thresholds typically obtained with PPLN doubly-resonant OPOs (DROs) and pump-enhanced single-resonant OPOs (PE-SROs) are still within the range of these pump sources. We have developed an external-cavity diode laser in a Littrow configuration, producing up to 60 mW at /spl sime/810 nm, and used this source to pump a PPLN DRO. Stabilised single-mode operation of the DRO for over five minutes was achieved using a servo-control system and was limited by the mechanical stability of the DRO. Previously, with a free-running diode laser, stabilisation was limited by mode-hopping of the pump to less than one minute.

Two different phase noise measurement techniques dedicated to the test of microwave free running oscillators are described and compared. The interest of an injection locking technique for the characterization of the close to carrier performance of low phase noise DROs is shown through different measurements examples on state-of-the-art DRO at C and X band.

Summary form only given. Optical parametric oscillators (OPOs) are attractive tools for high-resolution spectroscopy because of their tunability stability, narrow linewidth and efficiency. Doubly resonant OPOs (DROs) in particular offer low threshold operation with large continuous tuning ranges, typically tens of gigahertz. Their use for high-resolution spectroscopy in the infrared at Doppler-broadened resolution levels has been demonstrated. We report on the construction and characterization of a frequency-doubled DRO which, for the first time, emits in the visible. It exhibits excellent spectral purity and stability and is well suited for ultra-high resolution spectroscopy. A semi-monolithic MgO:LiNbO/sub 3/ DRO is pumped by a CW frequency-doubled monolithic ring Nd:YAG laser with up to 500 mW at 532 nm, producing up to 112 mW of signal power tunable from 962-1005 nm and up to 95 mW of idler power tunable from 1130-1190 nm. We have measured a free-running stability of less than 1 GHz for up to 20 hours in a single mode pair.

Novel millimeter-wave dielectric resonator oscillators (PRO) and dielectric resonator voltage controlled oscillators (DR-VCO) have been developed for communication systems. The authors have been developing DROs with a novel structure called PDIC (planar dielectric itegrated circuit), which layers are composed of a microstrip circuit substrate stacked on a high ?r dielectric resonator (DR) substrate with electrodes on both surfaces. The DR substrate and a pair of hollow patches on the electrodes form a dielectric resonator (TE010 mode DR). This paper focuses on the improvement of the temperature stability of the PDIC-DRO by controlling the material composition of the DR. An excellent temperature stability of oscillation frequency of less than 1ppm/deg C has been obtained for DRO and DR-VCO. The phase noise of the DRO and DR-VCO is - 100dBc/Hz and ?94 dBc/Hz at 100kHz offset respectively. The DRO or DR-VCO without PLL can be used for millimeter-wave sources of communication systems.

Based on the results obtained from monolithic MESFET oscillators with dielectric resonator stabilization (DROs) [1,2], PM-HFET oscillators with a similar topology have been realized and investigated at frequencies up into the W-band. As the active device quarter-micron InGaAs-GaAs HFETh have been used which have shown high power gain cutoff-frequencies up to 200 GHz. The design is carried out by using in-house developed software and is based on an equivalent circuit derived from the HFET S-parameter data measured up to 40 GHz. The output power of the oscillators is 10 mW and I mW at 37 GHz and 81 GHz, respectively. The oscillators show state-of-the-art phase noise in the mm-wave frequency range, at 37 GHz the phase noise is as low as ?97 dBc/Hz at 100 kHz off carrier.

Presented are the experimental and computational results of a study on a new kind of dielectric resonator oscillator (DRO). It consists of a cooled, cylindrically symmetric sapphire resonator surrounded by a metallic shield and is capable of higher Q's than any other dielectric resonator. Isolation of fields to the sapphire by the special nature of the electromagnetic mode allows the very low loss of the sapphire itself to be expressed. Calculations show that the plethora of modes in such resonators can be effectively reduced through the use of a ring resonator with appropriate dimensions. Experimental results show Q's ranging from 3 x 10 to the 8th at 77 K to 10 to the 9th at 4.2 K. Performance is estimated for several types of DROs incorporating these resonators. Phase noise reductions in X-band sources are indicated at values substantially lower than those previously available.