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The purpose of this paper is to find a closed relation for the phase noise of LC oscillators.

The governing equation of oscillators is generally a stochastic nonlinear differential equation. In this paper, a closed relation for the phase noise of LC oscillators was obtained by approximating the I–V characteristic of the oscillator with third-degree polynomials and analyzing its differential equation.

This relation expresses phase noise directly in terms of circuit parameters, including the sizes of the transistors and the bias. Next, for evaluation, the phase noise of the cross-coupled oscillator without tail current was calculated with the proposed model. In this approach, the obtained equations are expressed independently of technology by combining the obtained phase noise relation and g_m/I_D method.

A technology-independent method using the g_m/I_D method and the closed relationship is provided to calculate phase noise.

This paper aims to find a closed-form expression for the frequency and amplitude of single-ended ring oscillators when transistors experience all regions.

In this paper, the analytical relationships presented for ring oscillator amplitude and frequency are approximately derived due to the nonlinear nature of this oscillator, taking into account the differential equation that governs the ring oscillator and its output waveform.

In the case where the transistors experience the cut-off region, the relationships presented so far have no connection between the frequency and the dimensions of the transistor, which is not valid in practice. The relationship is presented for the frequency, including the dimensions of the transistor. Also, a simple and approximately accurate relationship for the oscillator amplitude is provided in this case.

The validity of these relationships has been investigated by analyzing and simulating a single-ended oscillator in 0.18 µm technology.

Because of the logic delay in the converter, the minimum turn on time of the switch is influenced by the constant time. When the inductor current gets to the threshold of the chip, the control signal will delay for a period. This makes the inductor current rising with the increasing of the clock and leads to the load current out of control. Thus, this paper aims to design an oscillator with a variable frequency protection function.

This paper presents an oscillator with the reducing frequency applied in the DC-DC converter. When the converter works normally, the operating frequency of the oscillator is 1.5 MHz. So the inductor current has enough time to decay and prevent the power transistor damaging. After the abnormal condition, the converter returns to the normal operating mode automatically.

Based on 0.5 µm CMOS process, simulated by the HSPICE, the simulation results shows that the frequency of the oscillator linearly decreases from 1.5 MHz to 380 KHz when the feedback voltage less than 0.2 V. The maximum deviation of the oscillator frequency is only 6 per cent from −50°C to 125°C within the power supply voltage of 2.7-5.5 V.

When the light load occurs at the output stage, the oscillator frequency will decrease as the load voltage drops. The test results shows that when the circuit works in the normal condition, the oscillator frequency is 1.5 MHz. When the load decreased, the operating frequency is dropped dramatically.

This paper aims to use the Matsuoka’s neural oscillators as the basic units of central pattern generator (CPG), and to offer a new CPG architecture consisting of a dual neural CPG of circular three links responsible for oscillator phase adjustment, to which an external neural oscillator is added, which is responsible for oscillator amplitude adjustment, to control foot depth to balance itself when treading on an obstacle.

It is equipped with a triaxial accelerometer and a triaxial gyroscope to obtain a real-time robot attitude, and to disintegrate the foot tilt in each direction as feedback signals to CPG to restore the robot’ horizontal attitude on an uneven terrain. The CPG controller is a distributed control method, with each foot controller consisting of a group of reciprocally coupling neural oscillators and sensors to generate different locomotion by different coupling patterns.

The experiment results indicated that the gait design method succeeded in enabling a steady hexapod walking on a rugged terrain, the mode of response is such that adjustments can only be made when the tilt occurs.

The overall control mechanism uses individual foot tilts as the feedback signal input to the neural oscillators to change the amplitude and compare against the reference oscillators of fixed amplitude to generate the foot height reference signals that can balance the body, and then convert the control signals, through a trajectory generator, to foot trajectories from which the actual rotation angle of servo motors can be obtained through inverse kinematics to achieve the effect of restoring the balance when traveling.

The controller design based on the bionic CPG model has the ability to restore its balance when its body tilts. In addition to the model’s ability to control locomotion, from the response waveforms of this experiment, it can also be noticed that it can control the foot depth to balance itself when treading on an obstacle, and it can adapt to a changing environment. When the obstacle is removed, the robot can quickly regain its balance.

This paper aims to present a simulation concept and an experimental verification of a novel sensor design for the shaft position measurement based on the eddy current principle and the phase-shift measurement. The simulation method for the sensor characteristic determination is presented. Possible application of a new sensor type is theoretically presented, verified in simulation and compared with experimental results.

Sensor is based on the injection-locking phenomenon between coupled oscillators. Only one sensor per axis is used for position measurement. A pair of the sensing and reference oscillators in the sensor is electrically coupled via the coupling resistor. A change in the inductance for the eddy current sensor is simulated in the finite element method (FEM) software Flux and behavior of the sensor circuit is simulated in the SPICE simulator software LTSpice program. Finally, the simulation results are compared with the measurements conducted on the laboratory test rig.

A novelty in this approach is the usage of only one sensor per axis compared to the well-known differential measurement of the position that uses the opposite pair of the sensing oscillators in the same axis. A methodology for the sensor characteristic determination is presented and experimentally verified.

A new variation of a coupled-oscillator eddy current sensor design is introduced. A simulation approach for the characteristic determination of the sensors based on the weakly coupled oscillators and the injection-locking mechanism is presented.

The purpose of this study is to compare two unsteady actuators: an oscillator and a sweeping jet. Both actuators can produce an oscillating jet of different amplitudes and frequencies without any moving parts, making them an attractive actuator concept. The Coanda effect phenomenon can explain the operating principles of these two unsteady actuators.

A numerical study was conducted to compare the amplitudes and frequencies of fluidic and sweeping jet (SJ) oscillators to obtain an efficient actuator to control separated flows at high Reynolds numbers. For this goal, two-dimensional unsteady Reynolds-averaged Navier-Stokes simulations were carried out using computational fluid dynamics (CFD) fluent code to evaluate the actuator performances. The discrete fast Fourier transform method determined the oscillation frequencies.

The oscillation frequencies gradually increase as the inlet pressure increases. The characteristics and dimensions of the vortices produced in the mixing chamber and feedback loops vary overtime when the injected fluid is swept sideways. The frequencies supplied by the SJ are stronger than those obtained by the fluidic oscillator, which may contribute to improving the aerodynamic performance at a lower power supply cost.

The existence of the splitter in the fluidic oscillator led to the production of separate pulses, which would be useful in various industrial applications, including active control of combustion and mixing processes while other applications such as flow separation control require SJs. With the latter actuator higher and interesting frequencies can be obtained, leading to efficient flow control.

The design of temperature‐compensated quartz crystal oscillators (TCXOs) in thick film hybrid technology is described. TCXOs controlled by varicap diodes are usually realised with discrete NTC thermistors and resistors. Data obtained by precision measurements of voltages on varicap diodes for the same oscillator frequencies over the operating temperature range are used for calculating values of the NTC thermistors and resistors. In most cases these values cannot be found in the Renard scale, with the result that manipulation or ‘juggling’ of values is necessary. The realisation of temperature‐compensating circuits in thick film technology has certain advantages, such as miniaturisation, better characteristics at high frequencies and in particular the possibility to trim thick film resistors and NTC thermistors to values calculated for each oscillator. The method of realisation of TCXOs in thick film hybrid technology was developed and verified on prototypes. The compensation curves were obtained by measuring compensation voltages for each oscillator over the operating temperature range from — 20°C to 70°C. From these data the values of resistors and NTC thermistors were calculated. A computer program was used to minimise frequency instability error as a function of six parameters (resistance). The frequency stability (Δf/f) of TCXOs obtained was better than ±2 ppm.

This paper aims to propose and demonstrate novel microphone sensors based on the frequency delta-sigma modulation (FDSM) technique, which replaces the conventional delta-sigma modulator in the delta-sigma analog-to digital converters. A key of the FDSM technology is to use a voltage-controlled oscillator (VCO) for converting an input analog signal to a 1-bit pulse-density modulated digital signal. High-performance sensors can be realized if the VCO is replaced by an oscillator whose oscillation frequency depends on an external physical parameter.

Microphone sensors are proposed based on FDSM that uses a suspended microstrip disk resonator, where the backside ground plane is replaced by a thin metal diaphragm. A resonant tunneling diode (RTD) oscillator is also used, as the performance of these sensors significantly depends on the oscillation frequency. To demonstrate the basic operation of the proposal, prototype devices were fabricated with an InGaAs/AlAs RTD.

A satisfactory noise shaping property, which is a significant nature of delta-sigma modulation, was demonstrated over three decades for the prototype device. A sound-sensing peak was also clearly observed when applying 1 kHz sound from a speaker.

High-performance ultrasonic microphone sensors can be realized if the sensors are fabricated by using a thin InP substrate with high-frequency oscillator design.

In this study, the authors proposed and experimentally demonstrated novel microphone sensors, which are promising as future ultrasonic sensors that have high dynamic range with wide bandwidth.

The purpose of this paper is to investigate a more robust ring oscillator. Less sensitivity to power supply variations is a target. This is important since low-quality ring oscillators could be exploited in numerous systems to reduce die costs.

The method in this work is large signal analysis. Delay time as the large signal parameter is calculated symbolically to explore dependency on a power supply voltage. Then simulations are performed to make a comparison. In this work, mathematical justifications are verified via HSPICE circuit simulator outputs, while 0.18 µm TSMC CMOS technology is exploited.

At least two combined configurations are presented with higher robustness. These circuits are more appropriate in noisy conditions. Both theoretical calculations and simulation results verify less sensitive oscillation against supply voltage ripples and temperature variations.

Introducing a band-switched inverter in combined configurations is contribution. In this way, three structures are presented which both show higher stability in oscillation frequency. The band switched delay time calculations are quite new and also the validity of the symbolical delay time approach is verified by circuit simulations.