Low Noise Oscillator Research Articles

LOW FREQUENCY NOISE PARAMETERS IN AN AlGaN/GaN HETEROSTRUCTURE WITH 33% AND 75% Al MOLE FRACTION

Transport and low frequency noise properties of undoped AlGaN/GaN high electron mobility transistor (HEMT) heterostructures with 33% and 75% Al mole fractions in the ohmic and non-linear regimes of applied voltages are studied. In contrast to the low Al mole fraction, the noise properties of 75 % content structures are not affected by passivation. At small voltages both kinds of structures demonstrate about the same level of l/f excess noise. Deviations from conventional flicker noise were observed at high applied voltages. Additionally, differences in noise behaviour between the two structures were revealed. In the 75% content structures, a noise level suppression was registered in the non-linear regime, which is important for the development of low noise oscillator circuits.

Characterization of the Jitter in a Mode-Locked Er-Fiber Laser and Its Application in Photonic Sampling for Analog-to-Digital Conversion at 10 Gsample/s

This paper compares two approaches for evaluating the amplitude and timing jitters of an Er-fiber laser mode-locked at 10 GHz. Using a low-noise oscillator as the clock drive for the mode-locking, relative amplitude jitter was measured as low as 0.0384% and timing jitter as low as 0.0153% (/spl Delta/f=100 Hz-40 MHz). Applying the mode-locked pulse train in a photonic sampling experiment at 10 Gsample/s, a spurious free dynamic range (SFDR) of /spl sim/48.5 dB (over the Nyquist bandwidth of 5 GHz) for multiple analog inputs at L band (1-2.6 GHz). These results correspond to an analog-to-digital conversion resolution of /spl sim/8 SFDR bits at 10 Gsample/s. Finally, the use of "instantaneous companding" is demonstrated to correct for third-order distortions generated by a Mach-Zehnder modulator used in the photonic sampling link.

High-Frequency Carrier Type Thin-Film Sensor Using Low-Noise Crystal Oscillator

We have developed a very sensitive high-frequency carrier-type magnetic field sensor based on the giant magneto-impedance effect available at lower frequencies. Our approach is to optimize the sensor structure so as to obtain high impedance. In addition, we optimize the carrier suppressing circuit using a low-noise crystal oscillator to reduce the phase noise of the lower offset frequency (under 1 kHz) as a carrier source. When a small ac magnetic field is applied to the sensor element, a very small AM signal can be detected using a carrier suppressing circuit with a low-noise crystal oscillator. A resolution of 1.7/spl times/10/sup -8/ Oe/Hz/sup 1/2/ was obtained at 501 kHz. The detectable magnetic field is limited by the thermal noise of room temperature. Resolutions of 1.5/spl times/10/sup -7/ Oe/Hz/sup 1/2/ at 1 kHz and a resolution of 1.1/spl times/10/sup -6/ Oe/Hz/sup 1/2/ at 110 Hz were demonstrated. The resolution was basically limited by the phase noise of the crystal oscillator.

A Survey of Heterojunction Bipolar Transistor (HBT) Device Reliability

Heterojunction bipolar transistor (HBT) technology has become a major player in wireless communication, power amplifier, mixer, and frequency synthesizer applications. HBTs extend the advantages of silicon bipolar transistors to significantly higher frequencies. Since the mid-1980s, HBT technology development has focussed on reducing cost and improving reliability which, in turn, led to numerous commercial products, such as prescalers, gate arrays, digital-to-analog converters, mux/demux chip sets, logarithmic amplifiers, RF chip sets for CDMA wireless communication systems, and power amplifiers for cellular communications. They have become a natural choice for very high frequency military applications requiring a high current drive, high transconductance, high voltage handling capability, low noise oscillator, and uniform threshold voltage. Emerging HBT technologies allow the integration of a large quantity of high performance RF circuits and high speed digital circuits on a single chip. This paper provides an overview of HBT device reliability issues.

Low-noise CMOS LC oscillator with dual-ring structure

A dual-ring structure of LC resonators is presented to improve the phase noise performance much further, keeping the multi-phase output capability. This dual-ring oscillator is fabricated in a 0.25 µm CMOS process and achieves the measured phase noise of −137 dBc/Hz at 1 MHz offset from a 2.27 GHz carrier.

A dual-gate FET subharmonic injection-locked self-oscillating active integrated antenna for RF transmission

A planar subharmonic injection-locked GaAs dual-gate MESFET (DGMESFET) self-oscillating active integrated antenna (AIA) is presented for RF transmission. The oscillation is obtained with one gate of the DGMESFET at 2.052 GHz, and the stabilization of the oscillation is achieved by injecting a small subharmonic low-noise signal into the other gate of the DGMESFET. Phase noise was measured to be -98 dBc/Hz at the 10 KHz offset. The structure was shown to have the potential in performing triple functions of radiation, low noise oscillation and mixing (or modulation), a capability required for low cost wireless systems such as RFID tags and indoor positioning systems.

GaAs FETs [microwave devices

The field effect transistor (FET) at microwave frequencies using GaAs has been a cornerstone of research in solid state microwave devices for the past 30 years. It is an established item in the microwave systems of today in such applications as low noise amplifiers, mixers, oscillators, power amplifiers, switches and multipliers. Indeed, many microwave systems would not be possible at their present day performance levels if it were not for the GaAs FET.

Theory and design of piezoelectric resonators immune to acceleration: present state of the art.

A typical low noise oscillator uses a crystal resonator as the frequency-determining element. An understanding of the fundamental nature of acceleration sensitivity in crystal oscillators resides primarily in understanding the behavior of the crystal resonator. The driving factor behind the acceleration-induced frequency shift is shown to be deformation of the resonator. The deformation drives two effects: an essentially linear change in the frequency-determining dimensions of the resonator and an essentially nonlinear effect of changing the velocity of the propagating wave. In this paper, the fundamental nature of acceleration sensitivity is reviewed and clarified, and attendant design guidance is developed for piezoelectric resonators. The basic properties of acceleration sensitivity and general design guidance are developed through the simple examples of "bulk acoustic wave (BAW) in a box" and "surface transverse wave (STW) in a box." These examples serve to clarify a number of concepts, including the role of mode shape and the basic difference between the BAW and STW cases. The design equations clarify the functional dependencies of the acceleration sensitivities on the full range of crystal resonator design and fabrication parameters.

CMOS RF integrated circuits at 5 GHz and beyond

A strong demand for wireless products, an insatiable thirst for spectrum that pushes carrier frequencies ever upward, and the constant quest for higher performance at lower power and cost, have recently driven the development of radio frequency integrated circuit (RFIC) technology in unprecedented ways. These pressures are stimulating novel solutions that allow RFICs to enjoy more of the benefits of Moore's law than has been the case in the past. In addition to regular raw transistor speed increases, the growing number of interconnect layers allows the realization of improved inductors, capacitors, and transmission lines. A deeper understanding of noise at both the device and circuit level has improved the performance of low noise amplifiers (LNAs) and oscillators. Finally, an appropriate raiding of circuit ideas dating back to the vacuum tube era enables excellent performance, even when working close to the limits of a technology. This paper surveys some of these developments in the context of low-power RF CMOS technology, with a focus on an illustrative implementation of a low-power 5-GHz wireless LAN receiver in 0.25-/spl mu/m CMOS. Thanks to these recent advances in passive components and active circuits, the blocks comprising the receiver consume a total of approximately 37 mW. These blocks include an image-reject LNA, image-reject downconverter, and a complete frequency synthesizer. The overall noise figure is 5 dB, and the input-referred third-order intercept (IIP3) is -2 dBm. To underscore that 5 GHz does not represent an upper bound by any means, this paper concludes with a look at active circuits that function beyond 15-20 GHz, and a characterization of on-chip transmission lines up to 50 GHz, all in the context of how scaling is expected to shape future developments.

High-Performance Surface Transverse Wave Resonators in the Lower GHz Frequency Range

Since the first successful surface transverse wave (STW) resonator was demonstrated by Bagwell and Bray in 1987, STW resonant devices on temperature stable cut orientations of piezoelectric quartz have enjoyed a spectacular development. The tremendous interest in these devices is based on the fact that, compared to the widely used surface acoustic waves (SAW), the STW acoustic mode features some unique properties which makes it very attractive for low-noise microwave oscillator applications in the 1.0 to 3.0 GHz frequency range in which SAW based or dielectric resonator oscillators (DRO) fail to provide satisfactory performance. These STW properties include: high propagation velocity, material Q-values exceeding three times those of SAW and bulk acoustic waves (BAW) on quartz, low propagation loss, unprecedented 1/f device phase noise, extremely high power handling ability, as well as low aging and low vibration sensitivity. This paper reviews the fundamentals of STW propagation in resonant geometries on rotated Y-cuts of quartz and highlights important design aspects necessary for achieving desired STW resonator performance. Different designs of high- and low-Q, low-loss resonant devices and coupled resonator filters (CRF) in the 1.0 to 2.5 GHz range are characterized and discussed. Design details and data on state-of-the-art STW based fixed frequency and voltage controlled oscillators (VCO) with low phase noise and high power efficiency are presented. Finally, several applications of STW devices in GHz range data transmitters, receivers and sensors are described and discussed.

Simulation of phase noise generated by white noise in 1.7 GHz CMOS LC oscillator

The phase noise resulting from upconversion of white noise in a CMOS LC oscillator is investigated. HSPICE simulations of phase noise resulting from the random-phase white noise in a 1.7 GHz CMOS LC oscillator have been performed and demonstrate that the phase noise resulting from the upconversion of white noise has a 1/f-dependence on the offset frequency and becomes larger as the white noise increases. The results provide a confirmation by circuit simulations of Leeson's empirical formula, and provide a technique for the design of low noise oscillators.

Low-noise monolithic Ku-band VCO using pseudomorphic HEMT technology

A low-noise pseudomorphic HEMT Ku-band oscillator with varactor frequency tuning and voltage power control is reported. The circuit size, including the varactor and the pads for on-wafer testing, is less than 0.7 mm/sup 2/. On-wafer oscillator measurements show a frequency tuning bandwidth of 600 MHz centered at /spl sim/15.2 GHz and an output power up to 17 dBm with more than 15 dB of power control. Phase noise of -87 dBc/Hz at 100 kHz has been obtained, which is an excellent result for a fully monolithic integrated Ku-band voltage-controlled oscillator (VCO).

The active device characterization and modelling problem in low phase noise microwave oscillator design

The conversion of low frequency noise into phase noise in a high frequency oscillator depends strongly on the active device type and operating conditions. Experimental set-ups are presented to achieve the choice of a transistor to be used in low noise oscillators and to study the correlation between phase noise and low frequency noise. Modelling guidelines are then described to help in the understanding of the noise conversion process. Simple rules of noise reduction are derived from simplified small signal models but the emphasis is put on more complete modelling approaches. These accurate models are affected by yet unsolved (or partially unsolved) problems such as : the influence of the large signal behaviour on the noise sources or the physically unacceptable cancellation of the phase noise in special biasing conditions.

Si/SiGe MMIC's

Silicon-based millimeter-wave integrated circuits (SIMMWIC's) can provide new solutions for near range sensor and communication applications in the frequency range above 50 GHz. This paper presents a survey on the state-of-the-art performance of this technology and on first applications, The key devices are IMPATT diodes for MM-wave power generation and detection in the self-oscillating mixer mode, p-i-n diodes for use in switches and phase shifters, and Schottky diodes in detector and mixer circuits. The silicon/silicon germanium heterobipolar transistor (SiGe HBT) with f/sub max/ values of more than 90 GHz is now used for low-noise oscillators at Ka-band frequencies. First system applications are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High performance direct coupled bandpass filters on coplanar waveguide

This paper describes the design and performance of shunt inductively coupled bandpass filters implemented on an open coplanar waveguide. This new structure exhibits low radiation loss due to the removal of the capacitively coupled gaps encountered in end or edge coupled filters. Unloaded Qs greater than 540 have been achieved in unshielded single section resonators at 4 GHz on very thin substrates. These high Qs enable the design of filters with low insertion loss and good stopband rejection. Applications include low insertion loss, high and printed filters where no screening is required, low noise oscillators and superconducting filters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-temperature superconducting resonators

Preliminary measurements on high-T(c) superconducting resonators are reported and why they are attractive candidates for incorporation in low-noise oscillators is discussed. Some of the important contributions to oscillator noise are reviewed and how they depend on the resonator parameters is shown. A preliminary YBaCu (3)O(7)/LaAlO(3) resonator with a Q of 9x10(4) at 6.9 GHz and 7x10(4) at 3.5 GHz has been fabricated. The temperature sensitivity, power dependence, and residual phase noise are discussed. An upper-limit on the coefficient of the 1/f component of fractional-frequency fluctuations has been measured to be -204 dB at 60 K.

A novel microwave limiter-discriminator: design and analysis

A new microwave discriminator that incorporates an efficient amplitude limiter is described. The amplitude limiting action is obtained from a pair of low-noise Gunn oscillators synchronized with the input microwave signal. The proposed limiter-discriminator works on the principle of phase-splitting action of the waveguide line, as in the case of a passive microwave discriminator. The figure of merit of the proposed discriminator is the highest among the passive and active discriminators reported in the literature. The implementation of the proposed limiter-discriminator can be easily extended to the millimeter-wave and sub-millimeter wave regions of the electromagnetic spectrum. >

Fundamentals of oscillator performance

The oscillator is arguably the most essential part of any communication system: it defines a channel frequency, or timing and synchronisation in a digital system. The phase noise of any oscillator has a fundamental lower limit. It limits the achievable efficiency of spectrum use and degrades the error rate in practical applications. Any low-noise oscillator can be described as a positive-feedback Q multiplier circuit. Such a model shows that phase noise is minimised if the square of the effective circuit Q and the signal-to-noise ratio in the oscillator are maximised. This simple fact is true for all oscillators and it provides the basis for more efficient and lower noise designs.

Microwave resonators incorporating ceramic YBaCuO helices

Measurements of the unloaded Q-factors of resonators incorporating YBaCuO helices are presented as a function of temperature. All of the bulk helices give unloaded Qs higher at 77 K for frequencies less than 1 GHz than equivalent wholly Cu structures. Approximate microwave modeling of the resonator gives surface resistances around 1 m Omega at 77 K and 500 MHz. Initial measurements on thick-film YBaCuO helices give Q values significantly lower than the bulk, probably due to dielectric loss in the zirconia substrate. The enhancement in Q over similar Cu resonators make these devices useful for demonstration purposes. For practical applications, however, it is unlikely that the improvement observed will affect the status of low-noise microwave oscillators and filters.

Transistor oscillators with impedance noise matching

A theory is derived which makes it possible to predict the carrier-to-noise ratio (CNR) of a transistor oscillator with real components depending on parameters of the active element and the oscillator circuit, which can be easily measured. The theory leads to certain new ideas for low-noise oscillator design which include the use of a multiple-stage active element and an impedance condition for noise matching. In this context the conditions for the use of GaAs FETs in low-noise oscillators are investigated. The resulting possibility of predicting the CNR depending only on transistor and circuit parameters is verified experimentally with seven different single-bipolar-transistor oscillators in the frequency range around 150 MHz. The measured values of the CNR show very good agreement with the values derived from theory. The differences between measured and calculated values are smaller than the measurement uncertainty of 3 dB.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>