Novel low-noise 'Fabry-Perot' transmission line oscillator

A low-noise 1.49 GHz oscillator which uses a novel inline transmission line resonator as the positive feedback element is described. A theory which shows how minimum sideband noise can be obtained from such an oscillator is presented, and the degradation of noise performance with circuit parameters is described. Close agreement between the theoretical and experimental results indicates that it is possible to use a simple linear theory in the accurate design of microwave oscillators with minimum sideband noise performance.<>     

A new low-noise 100-MHz balanced relaxation oscillator

A novel fully balanced architecture for high-frequency, low-noise relaxation oscillators is presented. Differential operation is achieved with the use of two grounded capacitors utilizing the circuit parasitics. Bypassing of the regenerative memory function in the oscillator benefits both high-speed and low-noise operation. A detailed analysis of phase noise in relaxation oscillators is performed. Results obtained from a test chip have verified the viability of the new oscillator and the developed phase-noise theory. The oscillator circuit has been realized in a medium-frequency (f_τ=3 GHz) bipolar process. The tuning range extends to 150 MHz. At an oscillation frequency of 115 MHz, measured phase noise was -118 dBc/Hz at 1-MHz distance from the carrier     

A series of InGaP/InGaAs HBT oscillators up to D-band

In this paper, the development of a series of fixed-frequency heterojunction bipolar transistor (HBT) oscillators from the W- to D-bands is reported. The oscillators are designed based on feedback theory with a small-signal equivalent circuit. This design method enables the achievement of high-output-power oscillators for the management of the power that is generated at the current source inside the HBT. We use a 1 μm×10 μm single-emitter InGaP/InGaAs HBT as an active device for each oscillator, and 50-Ω coplanar waveguides as transmission lines and resonators. Emitter output topology is adopted to reduce the chip size. The series of oscillators achieve the oscillation frequency of 74.8-146.7 GHz. To our knowledge, the 146.7-GHz fundamental oscillation frequency is the highest oscillation frequency achieved thus far using InGaP/InGaAs HBT technology. The output power of the 146.7-GHz oscillator is -18.4 dBm. The chip size of the oscillator is 731 μm×411 μm     

Planar FET oscillators using periodic microstrip patch antennas

An integrated oscillator/antenna is presented that uses a single microstrip leaky-wave structure as both the resonant and the radiating element. This resonant antenna is connected to a GaAs metal-semiconductor field-effect transistor which acts as the negative resistance element in the oscillator circuit. This type of oscillator is similar in its operating principle to one reported using Gunn diodes and a periodically notched dielectric image guide. This circuit exhibits the high DC-RF conversion efficiency that is typical of field-effect transistor oscillators. The planar circuit is simple and inexpensive to construct, occupies a small volume, and can conform to different surface profiles. Such circuits are suitable for use in millimeter-wave systems as well as at microwave frequencies. A design procedure is given, and the performance of X-band prototype circuits is reported. Prototype circuits showed a 9 dB isotropic conversion gain and 40 MHz tuning range at 9.5 GHz     

Microwave Integrated Oscillators for Broad-Band High-Performance Receivers

The design and development of a variety of microwave integrated circuit oscillators for use in integrated broad-band high-performance receiving systems is described. Examples of various thin-film microstrip oscillators directed to this application are provided including: 1) fixed-frequency Gunn-effect oscillators covering C to Ku band; 2) X-band varactor-tuned Gunn-effect oscillators providing up to 15 percent tuning bandwidth; 3) S-band step-tuned transistor oscillator assembly with better than half-octave digital tuning range; 4) L-band varactor-tuned transistor oscillator with almost an octave tuning range.     

Micromechanical oscillator circuits: theory and analysis

In this paper, detailed theoretical analysis of micromechanical Transresistance oscillator is presented. Analytical expressions are derived for the frequency pulling, critical transimpedance, maximum negative resistance, and start-up time constant of the Transresistance oscillator circuit which are useful for the design of micromechanical oscillators. These results are then used to study the frequency stability of Transresistance oscillator circuit and compare its operating conditions with that of the Pierce oscillator circuit which is widely used in micromechanical oscillators. The results conclusively show that the Transresistance oscillator has less start-up problems and better frequency stability than the Pierce oscillator. These results are then verified with a well-established circuit theory that compares the phase-frequency plots of the Pierce and Transresistance oscillator.     

Noise in SiGe HBT RF Technology: Physics, Modeling, and Circuit Implications

This paper presents an overview of the physics, modeling, and circuit implications of RF broad-band noise, low-frequency noise, and oscillator phase noise in SiGe heterojunction bipolar transistor (HBT) RF technology. The ability to simultaneously achieve high cutoff frequency (f/sub T/), low base resistance (r/sub b/), and high current gain (/spl beta/) using Si processing underlies the low levels of low-frequency 1/f noise, RF noise, and phase noise of SiGe HBTs. We first examine the RF noise sources in SiGe HBTs and the RF noise parameters as a function of SiGe profile design, transistor biasing, sizing, and operating frequency, and then show a low-noise amplifier design example to bridge the gap between device and circuit level understandings. We then examine the low-frequency noise in SiGe HBTs and develop a methodology to determine the highest tolerable low-frequency 1/f noise for a given RF application. The upconversion of 1/f noise, base resistance thermal noise, and shot noises to phase noise is examined using circuit simulations, which show that the phase noise corner frequency in SiGe HBT oscillators is typically much smaller than the 1/f corner frequency measured under dc biasing. The implications of SiGe profile design, transistor sizing, biasing, and technology scaling are examined for all three types of noises.     

Chaotic Oscillators Derived from Sinusoidal Oscillators Based on the Current Feedback Op Amp

A collection of novel chaotic oscillators displaying behavior similar to that of the chaotic Colpitts oscillator and requiring the same number and type of energy storage elements is proposed. The oscillators use as an active element the current feedback op amp (CFOA) mostly employed as a current negative impedance converter (INIC). Nonlinearity is introduced through a two-terminal voltage-controlled nonlinear device with an antisymmetric driving-point characteristic. The chaos generators are designed based on sinusoidal oscillators that have been modified for chaos in a semi-systematic manner. By using CFOAs, several attractive features are attained, in particular suitability for high frequency operation. Systems of third- and fourth-order ordinary differential equations describing the chaotic behaviors are derived. Experimental results, PSpice circuit simulations and numerical simulations of the derived mathematical models are included.     

MMIC 14-GHz VCO and Miller Frequency Divider for Low-Noise Local Oscillators

An MMIC voltage-controlled oscillator and an MMIC frequency divider are developed and applied to a 14-GHz low-noise local oscillator. To obtain both wide tuning range and low pulling figure, the source-follower FET circuit is used in the voltage-controlled oscillator. A wide-band balanced mixer and a filtering amplifier are integrated in a single chip and constitute the Miller frequency divider. -The MMIC's were assembled into a 14-GHz phase-locked loop in order to demonstrate that they will operate as key components of low-noise oscillators. It is shown experimentally that even for low-Q MMIC circuitry, the carrier noise of the oscillator is reduced enough for practical purposes such as space-borne heterodyne receivers, transmitters, and radio repeaters in Ku-band satellite communication systems. Thus, prospects are bright for development of single-chip microwave low-noise oscillators.     

Theoretical Study of Millimeter Wave Harmonic Oscillator Stabilized with a Transmission Cavity

An equivalent circuit model of millimeter wave second harmonic oscillator stabilized with a transmission cavity has been proposed for constructing analytical formulations between performance parameters of the oscillator and parameters of the circuit. The model consists of an equivalent circuit of fundamental wave and that of second harmonic wave. Each of the circuits comprises circuit models of main cavity, transmission waveguide, and transmission cavity. Absorbing material placed between the transmission waveguide and the transmission cavity can suppress additional resonances originated from transmission cavity. The behavior of the second harmonic oscillator can be effectively described by the circuit model. Furthermore, based on this model, mechanical tuning characteristics have been studied at first, and then analytical formulas for quality factor and efficiency depending on circuit parameters have been derived. The circuit parameters can be conveniently extracted by electromagnetic field simulation. Hence the formulas exhibit both compact form and enough accuracy. Thereafter, general rules of performance parameters varying with circuit parameters have been deduced for the harmonic oscillators. Then some design considerations have been derived according to the corresponding analysis. The equivalent circuit model is useful for designing and adjusting millimeter wave second harmonic stabilizing oscillator with a transmission cavity.     

Microwave Varactor Tuned Transistor Oscillator Design

An analysis is made of the common base microwave transistor oscillator circuit which uses a varactor in series with the colIector to tune over octave bandwidths. Equations are derived giving the required feedback capacitances and resonating elements required for octave tuning. Normally, the collector-emitter capacitance C/sub ce/ is made approximately equal to the transistor collector capacitance C/sub c/. The emitter-base capacitance C/sub eb/ is important only at very high frequencies. It is shown that a high-Q varactor must be used and that only a limited amount of collector-base capacitance C/sub cb/ may be added if the circuit is to be resonated over an octave. The output power for such a circuit is normally about 1/5 the maximum power available from the transistor. Experimental oscillators were made from 0.5 to 1 GHz and 1 to 2 GHz which substantially verified the analysis. Using the TIXS13 transistor, an output power of 200 mW was obtained from 430 to 860 MHz tuning from -2 to -115 volts. In the 1 to 2 GHz range a TIXS13 transistor oscillator was tuned from 1.09-1.96 GHz with about 40 mW power tuning from -2 to -115 volts. By use of a lower case capacitance varactor, the 1 to 2 GHz oscillator could be made to tune over the full octave.     

Rigorous Q-factor formulation for one- and two-port passive linear networks from an oscillator noise spectrum viewpoint

This brief characterizes one- and two-port passive networks from the viewpoint of oscillator design. A linear circuit theory derives the spectral spread due to RF noise from active devices. The formulation finds a frequency derivative function of logarithmic immittance that plays the key role of dominating the spectrum behavior. This leads to an explicit definition of the Q factor by referring to Leeson's basic oscillator model. The derived definition can provide an effective criterion for circuit topology and parameter optimization in low-noise oscillator design.     

Current conveyor based or unity gain cells based two integrator loop oscillators

Four alternative families of oscillators are considered in this paper, three of the families employ CCII or ICCII or combination of both and each family has sixteen oscillator circuit members. The fourth family uses unity gain cells and has four circuit members. Two alternative transformation methods are used in this paper for the generation of oscillators. The first one uses the adjoint circuit theorem to obtain a new family of current mode oscillators from a voltage mode oscillator circuit. The second transformation method uses the nodal admittance matrix (NAM) expansion to generate a grounded passive element oscillator family from an oscillator circuit, which employs a virtually grounded resistor. Although this paper has a tutorial nature it includes two new families of oscillators; one of them provides both current and voltage outputs and the other provides voltage outputs and is based on the use of voltage, current followers and inverters. Simulation results are included to support the analysis.     

Active Stabilization of Crystal Oscillator FM Noise at UHF Using a Dielectric Resonator (Short Papers)

A low-noise 600-MHz crystal oscillator circuit is described. It uses a dielectric oscillator as the dispersive element of a discriminator in an active frequency stabilization loop which reduces the near-carrier FM noise. The innovation in the circuit is an essentially noiseless active carrier suppression loop, which allows maximum utilization of a low-noise RF amplifier to reduce the discriminator threshold (Delta f/sub rms/) to 2.5x10-5 Hz in a 1-Hz bandwidth. The FM noise 1 kHz from the carrier was reduced by 44 dB to this threshold, equivalent to a phase-noise spectral density of -152 dBc/Hz.     

Squeezed state generation using cryogenic InP HEMT nonlinearity

This study focuses on generating and manipulating squeezed states with two external oscillators coupled by an InP HEMT operating at cryogenic temperatures. First, the small-signal nonlinear model of the transistor at high frequency at 5 K is analyzed using quantum theory, and the related Lagrangian is theoretically derived. Subsequently, the total quantum Hamiltonian of the system is derived using Legendre transformation. The Hamiltonian of the system includes linear and nonlinear terms by which the effects on the time evolution of the states are studied. The main result shows that the squeezed state can be generated owing to the transistor’s nonlinearity; more importantly, it can be manipulated by some specific terms introduced in the nonlinear Hamiltonian. In fact, the nonlinearity of the transistors induces some effects, such as capacitance, inductance, and second-order transconductance, by which the properties of the external oscillators are changed. These changes may lead to squeezing or manipulating the parameters related to squeezing in the oscillators. In addition, it is theoretically derived that the circuit can generate two-mode squeezing. Finally, second-order correlation (photon counting statistics) is studied, and the results demonstrate that the designed circuit exhibits antibunching, where the quadrature operator shows squeezing behavior.     

J-Band Transferred-Electron Oscillators

An equivalent circuit for a J-band transferred-electron oscillator containing lumped and distributed elements is proposed. Using element values obtained independently, the equivalent circuit is shown to have broad-band applicability and is capable of explaining, in a strictly quantitative fashion, frequency saturation and the loss or absence of circuit-controlled oscillation. It is shown that the S4 type of encapsulation places severe constraints on the mounting structure and is not ideally suited to the J-band waveguide oscillator for optimum power-frequency characteristics over a broad band. The analysis of the full equivalent circuit given does, however, permit analytic solutions for important oscillator design parameters such as mounting post diameter, which enables simple post-mounted J-band oscillators that are free from frequency saturation and loss of circuit-controlled oscillation in the band to be easily designed.     

A theory of noise in GaAs FET microwave oscillators and its experimental verification

A theory has been developed which provides an entirely analytical approach to the calculation of AM and FM noise in free-running GaAs FET microwave oscillators. The theory is based on the model that low-frequency device noise is mixed with the carrier signal via the nonlinearity of the FET and upconverted to microwave frequencies. Because of the analytical nature of the theory, all the important device and circuit parameters on which the noise generation depends are explicitly given. Two GaAs FET oscillators have been fabricated and used to investigate the FM noise. The theory predicts well both the spectral dependence and the absolute magnitude of the FM noise in both oscillators. The noise performance of the oscillators differs by 19 dB. The theory indicates that no single factor is responsible for this, and moreover that attention should be given to the optimization of many device and circuit features in the design of a low noise FET oscillator.     

A high-frequency electronically tunable quadrature oscillator

An architecture composed of mutually regenerative oscillators is introduced. It has been used to design a low-noise high-frequency voltage-controlled oscillator (VCO) capable of producing two output signals in quadrature with essentially identical properties. The phase relation between the quadrature outputs is frequency dependent and extremely stable. A novel way of coupling the regenerative oscillators is suggested in order to improve the frequency stability of the coupled oscillator system. Results obtained from a test chip have verified the viability of the oscillator concept. The oscillator circuit has been realized in a medium-frequency bipolar process. The tuning range extends to 500 MHz. At an oscillation frequency of 200 MHz, measured phase noise was -121 dBc/Hz at 1-MHz distance from the carrier.<>     

Analysis of an experimental technique for determining Van der Polparameters of a transistor oscillator

The Van der Pol (VDP) model of a transistor oscillator describes the behaviour of the oscillator with three parameters. When operating in steady state, only two parameters can be determined by spectrum analysis, these being the oscillation frequency and amplitude of oscillation. In this paper, a technique for measuring the other VDP parameter is examined. In this approach, a periodically modulated voltage is added to the bias of the oscillator to perturb the operational state. A theoretical derivation shows that the power spectrum of the perturbed oscillator contains additional information for determination of the other VDP parameter. A simple analytical perturbation formula predicts the oscillator's response to the ramped bias. Our experimental results agree with the analytical perturbation solution and therefore, this allows one to read off the other VDP parameter from the experimental data. The VDP model allows one to predict the behaviour of coupled transistor oscillators more accurately and simply than does the traditional large-signal model of the transistor. This VDP model will simplify oscillator array design since the number of parameters needed to describe each oscillator is reduced from that which would be required using a large-signal circuit model     

Design of Cryogenic SiGe Low-Noise Amplifiers

This paper describes a method for designing cryogenic silicon-germanium (SiGe) transistor low-noise amplifiers and reports record microwave noise temperature, i.e., 2 K, measured at the module connector interface with a 50-Omega generator. A theory for the relevant noise sources in the transistor is derived from first principles to give the minimum possible noise temperature and optimum generator impedance in terms of dc measured current gain and transconductance. These measured dc quantities are then reported for an IBM SiGe BiCMOS-8HP transistor at temperatures from 295 to 15 K. The measured and modeled noise and gain for both a single-and two-transistor cascode amplifier in the 0.2-3-GHz range are then presented. The noise model is then combined with the transistor equivalent-circuit elements in a circuit simulator and the noise in the frequency range up to 20 GHz is compared with that of a typical InP HEMT.