Showing papers on "Relaxation oscillator published in 2006"

A 0.8V 1.52MHz MSVC Relaxation Oscillator with Inverted Mirror Feedback Reference for UHF RFID

Abstract: A 0.8V nano-power relaxation oscillator for EPC standard UHF RFID transponder is presented. A low-voltage inverted mirror feedback VGS/R reference is proposed to provide correlated current and voltage references for the oscillator. As a result, the oscillator frequency is solely determined by the resistor in the reference and the timing capacitor to meet the frequency tolerance specification. Meanwhile, to minimize the power consumption, a minimum-supply-voltage-constraint (MSVC) design criterion is proposed to minimize the required supply voltage. The inverted mirror feedback technique reduces the headroom requirement of the traditional VGS /R to meet the MSVC. Measurement results show that the entire oscillator requires a minimum supply voltage of 0.8V in the prototype chip fabricated in CMOS 0.13mum technologies. The measured oscillation frequency is 1.52MHz with 400nA total current consumption. The chip area is 13400mum2

Analysis of emitter (source)-coupled multivibrators

Abstract: The popular emitter-coupled multivibrator and its MOS variant are analyzed using the classical discontinuity theory. Accurate formulas for predicting their relaxation oscillation are obtained solving the nonlinear circuit equation, which is derived finding the voltage-current characteristic of the nonlinearity connected to the timing capacitor. Then, using a small-signal equivalent circuit accounting for the intrinsic capacitances of the devices, we investigate the high-frequency behavior of these circuits finding the oscillation start-up condition. We show that they can exhibit a completely different behavior, similar to a series LC-tuned oscillator, without using an inductor. Numerical simulations are performed showing that the presented formulas are more accurate than the existing ones and that both behaviors are possible

Multiscroll Chaotic Oscillators: The Nonautonomous Approach

Abstract: A novel technique for designing chaotic oscillators capable of producing multiscrolls is presented The technique is based on multilevel-logic pulse-excitation A modified forced Van der Pol oscillator, a forced active tank resonator, and a forced cross-coupled oscillator are given as design examples

Capacitive angular-position sensor with electrically floating conductive rotor and measurement redundancy

Abstract: This paper presents a capacitive angular-position sensor with a contactless electrically floating conductive rotor and an interface electronic circuit that is designed to maximize the performance/cost ratio. The sensor includes two separate and independent measurement sections that sense the same angle and provide redundancy in critical applications. The electronic interface is based on a relaxation oscillator that, for each of the two sections, measures an appropriate quantity that relates capacitance ratio to angular position and provides a dc output voltage that varies ratiometrically with respect to the supply voltage. The sensor was built in a version with /spl plusmn/11/spl deg/ measuring range for each section. Experimental tests showed a linearity better that 1% of the span.

A Time-Domain Model for Predicting the Injection Locking Bandwidth of Nonharmonic Oscillators

Abstract: A delay-based model in the time domain is introduced to describe injection locking in nonharmonic oscillators, such as ring or relaxation oscillators. Using this model, the locking bandwidth of differential ring oscillators is derived. The model predictions are verified against simulations and measurements of a four-stage ring oscillator circuit built using discrete components

Ring oscillator made of organic thin-film transistors produced by self-organized process on plastic substrate

Abstract: The authors studied the fabrication of a ring oscillator consisting of organic inverters showing no hysteresis in output characteristics. They designed and fabricated the ring oscillator with bootstrapping inverters made of pentacene organic thin-film transistors on plastic produced by self-organized process, exhibiting the field-effect mobility of ∼0.6cm2∕Vs, on/off current ratio of 107, and threshold voltage of −5V. The oscillation frequency of 3kHz and signal propagation delay of 15μs per stage were achieved for an 11-stage oscillator with a supply voltage of 20V.

Relaxation oscillator based keypad decoder

Abstract: The keypad interface element of this invention uses a relaxation oscillator and a digital keypad processor having a counter/timer to decode specific keys The RC portion of the relaxation oscillator includes a resistance ladder and a set of momentary on pushbutton switches disposed change resistance dependent upon which key is pressed This causes the relaxation oscillator to produce an output signal having a corresponding frequency The counter/timer of the digital keypad processor produces a count corresponding to the oscillator frequency The digital keypad processor latches and holds a binary number specifically identifying the depressed key A state machine in the digital keypad processor provides transient-free, noise immune keypad decoding

Digital CMOS built-in temperature sensor

Abstract: The invention relates to a temperature sensor of a digital CMOS sheet in the field of temperature monitoring domain. It uses the linear relationship between the transistor critical voltage and the temperature to separately design two project temperature sensing circuit based on the relaxation oscillator and the Schmitt trigger. The accuracy of the two temperature sensors are below 1 degree. It adopts all CMOS structure at the same time.

Analog circuit and method for multiplying clock frequency

Abstract: A signal generating circuit includes a relaxation oscillator operating to alternately generate a first ramp signal that is periodic at a frequency of the relaxation oscillator and a second ramp signal that is periodic at the frequency of the relaxation oscillator and is out of phase with respect to the first ramp signal The first ramp signal is compared to a first reference voltage and the state of a first flip-flop is changed if the first ramp signal exceeds the first reference voltage. The second ramp signal is compared to the first reference voltage and the state of a second flip-flop is changed if the second ramp signal exceeds the first reference voltage. The first flip-flop is reset in response to a first level of the first ramp signal and the second flip-flop is reset in response to a second level of the second ramp signal. A logical ORing function is performed on an output of the first flip-flop and an output of the second flip-flop to produce an output signal having a frequency that is a multiple of the relaxation oscillator frequency.

Application of coupled neural oscillators for image texture segmentation and modeling of biological rhythms

Abstract: The role of relaxation oscillator models in application fields such as modeling dynamic systems and image analysis is discussed. A short review of the Van der Pol, Wilson-Cowan and Terman-Wang relaxation oscillators is given. The key property of such nonlinear oscillators, i.e., the oscillator phase shift (called the Phase Response Curve) as a result of external pulse stimuli is indicated as a fundamental mechanism to achieve and sustain synchrony in networks of coupled oscillators. It is noted that networks of such oscillators resemble a variety of naturally occurring phenomena (e.g., in electrophysiology) and dynamics arising in engineering systems. Two types of oscillator networks exhibiting synchronous behaviors are discussed. The network of oscillators connected in series for modeling a cardiac conduction system is used to explain causes of important cardiac abnormal rhythms. Finally, it is shown that a 2D network of coupled oscillators is an effective tool for segmenting image textures in biomedical images.

Drive circuit for a voltage controlled differential oscillator

Abstract: A drive circuit (40) for a voltage controlled differential oscillator using a negative resistance circuit (42) for driving the resonator circuit (30) of the voltage controlled differential oscillator. Opposite sides of the resonator circuit are connected to the negative resistance circuit with respective coupling capacitors (44, 46) so as to provide DC isolation between the resonator circuit and the negative resistance circuit. The negative resistance circuit is provided with an amplifier having a gain greater than unity so as to compensate for the degradation in negative resistance resulting from the coupling capacitors. The voltage controlled oscillator may be used in mobile telephones, in radio receivers and in DVB-H tuners/receivers.

Oscillator Arrangement and Method for Generating a Periodic Signal

Abstract: An oscillator arrangement is specified, in which a relaxation oscillator is refined to the extent that the comparator ( 2 ) to be used for comparing the voltage across a charge storage device ( 1 ) with a switching threshold (V TH ) is a current comparator with two current branches ( 5, 6 ). One of these two current branches is used in the present case for guiding a charging or discharging current of the charge storage device ( 1 ). In this way, a current branch is eliminated, so that the proposed principle is preferably suitable for so-called ultra low power applications.

Explaining Hysteresis in Electronic Circuits: Robust Simulation and Design Examples

Abstract: We show how the hysteresis behavior in electronic circuits can be explained in a robust manner using PSpice transient simulations. Furthermore, we design a novel circuit for three-segment nonlinear characteristic shaping and show how this circuit can be used to produce hysteresis loops. The realization of relaxation oscillators is then given as a typical application.

Explaining hysteresis in electronic circuits

Abstract: We show how the hysteresis behaviour in electronic circuits can be explained in a robust manner using PSpice transient simulations. Furthermore, we describe a simple circuit for three-segment nonlinear characteristic shaping and show how this circuit can be used to produce hysteresis loops. The realisation of relaxation oscillators is then given as a typical application.

High resolution auto-tuning for a voltage controlled oscillator

Abstract: According to one exemplary embodiment, an auto-tuning circuit (1 04) coupled to a voltage controlled oscillator (102) in a phase locked loop, where the voltage controlled oscillator is coupled to a capacitor array (105), includes a prescaler circuit (106) configured to provide a divided voltage controlled oscillator frequency, where the prescaler circuit is used in the phase locked loop during fine tunin of the voltage controlled oscillator in the auto-tuning circuit during coarse tuning of the voltage controlled oscillator. The auto-tuning circuit further includes a digital processing logic circuit (108) coupled to the prescaler circuit and configured to determine a capacitance of the capacitor array by comparing comp-cnt to a pre-determined value, where comp-cnt is determined by a number of cycles of the divided voltage controlled oscillator frequency that occur in a calibration interval.

Oscillator arrangement and method for producing a periodic signal

Abstract: The invention relates to an oscillator arrangement. The aim of the invention is to improve a relaxation oscillator. For this purpose, the comparator (2) for comparing the voltage on a charge accumulator (1) with a switch limit (VTH) is a current comparator having two current paths (5, 6). One of said current paths is adapted to carry a charge or discharge current of the charge accumulator (1). In this manner, one current path is eliminated, thereby rendering the principle preferably suitable for so-called ultra-low power applications.

Injection-lock dynamics in non-harmonic oscillators

Abstract: A delay-based time-domain model is used to predict the locking dynamics in injection-locked non-harmonic oscillators, such as ring or relaxation oscillators. The locking dynamics predicted by the model are verified against simulations and measurements of a four-stage ring oscillator circuit built using discrete components.

Compact CMOS VCO using a transistor for frequency control

Abstract: A compact CMOS voltage-controlled relaxation oscillator circuit is presented in this paper. The frequency control is fulfilled by using a single MOSFET to control the charging and discharging currents of a timing capacitor. This paper investigates and demonstrates the proposed control mechanism. The proposed VCO was fabricated using 0.18 μm CMOS technology and the fabricated VCO has a compact core size of only 80μm × 200μm, or 0.016mm2. A linear tuning range from 650 MHz to 840 MHz, or a 28% range was achieved by the single MOSFET's control from a 1.8V DC supply voltage. The output power was −14.5 dBm with only ±1 dB variation in this tuning range. The corresponding power consumption was measured to be 5.4mW. Moreover, the VCO free-running frequency can be increased beyond 1.1 GHz by using higher DC supply.

The Design ofWave Shape for Coupled Van del Pol Oscillators

Abstract: To make a central pattern generator (CPG) for articulated robots, we discuss Van del Pol (VDP) oscillator. It is difficult to analyze the output of VDP oscillator. The parameter design of VDP oscillator is considered with two cases which are single oscillator and two oscillators coupled with respect to one another, according to some numerical simulations.

A design and analysis of high performance voltage controlled oscillators

Abstract: The voltage controlled oscillator (VCO) is one of the most important building blocks in modern communication applications such as microprocessor clock generation, wired and wireless communications, system synchronization, and frequency synthesis. The design of high performance VCOs has been increasingly more important and still is an active research area. Research on VCOs for the past decade has been concentrated in the areas of higher frequency, lower phase noise, low power, low operating voltage, and increased tuning range. However many of these objectives can be only achieved at the expense of some other objectives. This thesis analyzes the design of high performance of inductor-capacitor (LC) tank and ring VCOs. First the basics of both LC and ring VCOs are reviewed. Then through the basics, new LC VCO topologies and circuit tricks are derived and analyzed. The design, simulation, and layout guidelines are also provided. Finally, the circuit techniques used in both regular and quadrature VCOs and simulation results of regular inductor and symmetric inductor designs are compared. Next, the several single-ended and differential ring VCO topologies are reviewed and pros and cons for each type are provided. From the basic topologies, a new ring VCO cell topology is then introduced, along with the bias circuit, output buffers, and divider. A three stage VCO based on the new topology is designed and simulated in both thick-oxide and thin-oxide devices in 65nm CMOS SOI process. The results of thick and thin oxide devices are compared and confirmed the usability of the new ring VCO cell topology. Finally, a conclusion of the design of high performance LC and ring VCOs is drawn and new directions of research are predicted.

Synchronization of Van der Pol Oscillator By External Voltage of Double Frequency

Abstract: Synchronization of the van der Pol oscillator is performed by an external sinusoidal voltage source of double frequency connected is series with the power supply and the oscillator. Modifying the oscillator effective supply voltage, this source modifies the coefficients of the van der Pol oscillator differential equation, and synchronizes the oscillator. The conditions and borders of synchronization are considered.

Synchronization of Mechanical Systems with a New Van der Pol Chaotic Oscillator

Abstract: By applying the twisting algorithm, synchronization between a DC motor and a new chaotic Van der Pol oscillator is presented. A state of the proposed new chaotic oscillator is synchronized with the shaft position of a DC Motor. Applications of tracking control of mechanisms with chaotic signals (the synchronization problem) have been of interest in many areas where some mechanical vibrations are required, like: washer machines, mixing liquids, blender machines, vibration bands for transportation, etc. This, because the performance task is improved by the richness of frequency contents on chaotic signals. Experimental results are shown to support our main results, where a DC Pitman motor is synchronized with an analog circuit implementation of the proposed chaotic oscillator.

The Structure of Instantaneous Phase Resetting in a Neural Oscillator

Abstract: In order to ultimately gain an understanding of the central pattern generators (CPG) involved in rhythmic motor activity such as locomotion and respiration it is necessary to understand the phase resetting behavior of the neural oscillators that comprise such circuits. In this study, we ignore action potential generation and instead focus on the underlying oscillations whose plateaus comprise the bursts and whose troughs comprise the interburst hyperpolarizations. We have examined the structure of phase resetting in neural oscillators. As an illustrative example, we will use Morris-Lecar oscillator, which, despite its simplicity, reproduces with sufficient accuracy the membrane potential envelope of a neural oscillator. The qualitative characterization of a limit cycle oscillator as a phase oscillator, a relaxation oscillator, or an intermediate determines the relationship between time elapsed (temporal phase) and distance traversed along the limit cycle (geometric phase). A mapping between geometric phase and temporal phase was found to provide insight into the shape of the phase resetting curve (PRC).

On-chip R-C time constant calibration

Abstract: An integrated tuner includes circuitry to receive a television signal, a quadrature mixer coupled to the output of the circuitry, a polyphase filter coupled to the output of the quadrature mixer, a relaxation oscillator, and a digital calibration module. The relaxation oscillator generates a clock having a period that is directly proportional to the on-chip RC time constant. The clock is fed into a counter of the digital calibration module. The counter is started and stopped at predefined time intervals by a finite state machine. The finite state machine updates the calibration code based on a successive approximation algorithm according to the end count results received from the counter. The digital calibration module outputs the updated calibration code to the polyphase filter and to the relaxation oscillator.

Triple-input relaxation oscillator with differential controllability

Abstract: There are provided relaxation oscillators and methods for controlling the same. A relaxation oscillator includes a load device, a switching device, a fine-tuning varactor, and a current source. The load device is configured to provide a variable oscillator output based on a variable input reference voltage. The switching device is connected in signal communication with the load device and is configured to become active and inactive based on the variable oscillator output. The fine-tuning varactor is connected in signal communication with the switching device and is configured to provide fine-tuning of the variable oscillator output when the switching device is active. The current source is connected in signal communication with the switching device and is configured to provide coarse-tuning of the variable oscillator output when the switching device is active.

Method for calibration of an oscillator for a microcontroller chip operation

Abstract: To calibrate an oscillator for microcontroller chip operation, an RC circuit is coupled to the microcontroller circuitry and a voltage signal is applied to the capacitor for changing the voltage across the capacitor. The voltage value across the capacitor is measured and compared to an expected voltage value. Adjustments to the frequency of the clock signal generated by the oscillator are made in response to the comparison.

A GaAs Acoustic Sensor Based On Resonant Tunnelling Diodes

Abstract: This paper reports a novel GaAs cantilever acoustic sensor based on AlAs/In1-xGa1-xAs/GaAs resonant tunneling diode (RTD) with a frequency output. The RTD is incorporated in a 10 mum thick cantilever diaphragm and the fabrication technology of the cantilever diaphragm is based upon the micromachined control holes technology. A relaxation oscillator is obtained with the RTD biased in the negative differential resistance (NDR) region. Pressure applied to the RTD changes the frequency of oscillation due to the shift in current-voltage characteristics. The main feature of this sensor type is the direct frequency output and the sensitivity can be up to 102KHz/KPa.

Low noise high dynamic range pixel architecture in amorphous silicon technology for diagnostic medical imaging applications

Abstract: The vast majority of commercially available flat panel digital x-ray ~magers are based on flat panel amorphous silicon (a-Si) thin film transistor (TFT) switch pixels that are derived from active matrix liquid crystal display (AMLCD) technology. In this thesis, we develop on-pixel analog-to-digital converters (A/D's) as alternate pixel architectures for large area digital x-ray imagers to incorporate off-panel components into the on-panel integrated circuit. The higher level of integration can lead to lower complexity and costs, higher speeds and better imager performance. Different voltage controlled oscillators (VCOs) were considered in this thesis including an LC tank oscillator, a relaxation oscillator, and a ring oscillator. Ring oscillators became the choice for on-pixel A/D's in this thesis due to their compact nature and higher frequency output for amorphous silicon thin film transistor based circuits. Measured results for voltage to frequency gain and estimations of phase noise and metastability are presented.