Showing papers on "Relaxation oscillator published in 1994"

On-chip voltage controlled oscillator

Abstract: An on-chip voltage controlled oscillator for use in an analog phase locked loop receives power from a voltage regulator which greatly reduces the noise seen by the voltage controlled oscillator. The voltage controlled oscillator has a DC bias section which supplies a relatively constant current to the multivibrator to assure a minimum operating frequency. A control signal is used to provide additional current which increases the speed of oscillation. The bias current reduces the transfer characteristics (MHz/volt) of the voltage controlled oscillator making it more immune to noise in the control signal.

Wide frequency range CMOS relaxation oscillator with variable hysteresis

Abstract: A voltage controlled oscillator (VCO) which may be adjusted to provide oscillatory signals for a wide range of frequencies includes a relaxation oscillator in which a ramp signal is compared to a reference threshold which exhibits hysteresis. The frequency of the oscillator is changed by varying the hysteresis range of the threshold level and by changing the rate at which the ramp is generated. At higher frequencies, the signal processing delay through the comparator is a factor in determining the frequency of the signal produced by the oscillator. Current sources internal to the oscillator are controlled by a reference potential that is generated from an externally supplied band-gap reference potential. The VCO is used in a phase-locked loop which includes a charge pump circuit that accumulates charge on a capacitor responsive to limited-width pulses applied to a current source which is controlled by the reference potential generated in the VCO.

(Double) relaxation oscillation SQUIDs with high flux‐to‐voltage transfer: Simulations and experiments

Abstract: Relaxation oscillation superconducting quantum interference devices (SQUIDs) (ROSs) and double relaxation oscillation SQUIDs (DROSs) have been fabricated and characterized The SQUIDs are based on hysteretic Nb/Al,AlOx/Al/Nb Josephson tunnel junctions The relaxation oscillations were simulated by computer By these simulations the minimum and maximum values of the shunt inductance at which the relaxation oscillations persist have been determined for different values of the shunt resistance and of the critical current and capacitance of the junctions The transfer from flux to dc voltage in ROSs increases linearly with the shunt resistance The operation range of the shunt inductance, however, becomes smaller with increasing shunt resistance In ROSs with a SQUID inductance of 20 pH, a maximum voltage modulation width of 400 μV and a flux‐to‐voltage transfer δV/δφ of 4 mV/φ0 have been obtained Two ROSs have been operated in a simple flux‐locked loop with direct voltage readout The experimental white flu

Relaxation oscillator and core conductor models are needed for understanding of GI electrical activities.

Abstract: This review examines the applicability of modeling of intestinal electrical activities (slow waves or pacesetter potentials) by coupled relaxation oscillator models, in comparison to a “multidimens...

Micro power R-C relaxation oscillator

Abstract: An R-C relaxation oscillator having two comparators and a silicon controlled rectifier dissipates very low average power without resulting in frequency instabilities due to circuit propagation delays. A timing capacitor CT is charged through a timing resistor RT. The first comparator compares the voltage across the timing capacitor with an upper threshold voltage VTH. When the voltage across the timing capacitor crosses the upper threshold voltage, the comparator turns on the silicon controlled rectifier, which causes the capacitor to discharge the voltage that it has stored. The second comparator turns off the silicon controlled rectifier when the voltage across the timing capacitor falls below a lower threshold voltage VTL. The silicon controlled rectifier also provides boosted comparator bias current during the discharge phase, enabling the second comparator to respond quickly to the lower threshold voltage crossing and allowing fast capacitor discharge (therefore narrow clock pulses) and increasing frequency stability.

Method for limiting the frequency of a voltage-controlled oscillator in a control circuit of a resonant converter switched-mode power supply, and control circuit for a resonant converter switched-mode power supply

Abstract: A method for limiting the frequency of a voltage-controlled oscillator in a control circuit of a resonant converter switched-mode power supply includes adjusting a delay time of a delay element disposed in a feedback branch of the voltage-controlled oscillator with a signal indicating a transition from negative to positive values of a current through an oscillating circuit of the switched-mode power supply. A resonant converter switched-mode power supply has an output voltage and an oscillating circuit with a current. A control circuit for the resonant converter switched-mode power supply includes a control amplifier being acted upon by the output voltage and by a reference voltage. A voltage-controlled oscillator is connected to and triggered by the control amplifier. A comparator detects a transition from positive to negative values of the current in the oscillating circuit. A flip-flop has a setting input being connected to and triggered by the voltage-controlled oscillator and has a reset input being connected to and triggered by the comparator. A delay element has a variable delay time and is triggered by a signal indicating a transition from negative to positive values of the current in the oscillating circuit.

Communications Using Chaotic Frequency Modulation

Abstract: Chaotic Frequency Modulation (CFM) provides the basis for a nonlinear communications system with (1) good noise suppression and (2) analogue signal encryption for private and secure communications links. CFM is a generalization of conventional Wideband Frequency Modulation (WFM) where the information about modulation samples mk are contained in the lengths of the periods pk for the kth cycle of the WFM waveform. A WFM modulator produces waveform periods described by an invertible function of the form pk=F(mk). Chaotic FM uses a map of the pulse periods to produce a noise-like pulse train even with a constant signal. The basis for CFM is a function pk=F(mk; pk−1, pk−2, …, pk−i), where i is the dimensionality of the map. A practical realization for a CFM transmitter employs an autonomous chaotic relaxation oscillator (ACRO) circuit for use as a chaotic voltage-controlled oscillator (CVCO). The ACRO is simple to construct, consisting of only two capacitors, one inductor, a bistable nonlinear element, and a modulated current source. The CVCO period (pk) is a nonlinear function of the current (mk) and the two previous pulse periods. Demodulation requires the use of at least three successive waveform-periods. Experimental and theoretical studies of the CVCO circuit have shown that (1) the ACRO return maps of pulse periods are embedded in three dimensions, (2) chaotic outputs are difficult to decode without prior knowledge of the circuit parameters, and (3) demodulation may be accomplished with a digital signal processor.

Receiver with function to adjust local frequency following reception frequency

Abstract: A receiver which has a linear approximation expression showing a relationship between the frequency deviations and corresponding changes to the voltage which is to be supplied to the voltage controlled reference oscillator to adjust the deviation following a reception frequency. The frequency deviation of the voltage controlled temperature compensated crystal oscillator is calculated based on the count values of the counters which count the frequency of the second local oscillator and the second intermediate frequency. The control voltage supplied to the voltage controlled temperature compensated oscillator is changed based on the linear approximation expression. Further, the approximation expression is represented as a series of powers of 2 based on a sensitivity coefficient of the voltage controlled reference oscillator. The approximation expression is changed by renewing the sensitivity coefficient of the voltage controlled reference oscillator. Moreover, in addition to the control of the voltage controlled reference oscillator, the second local oscillator is controlled in the similar way of the control of the voltage controlled temperature compensated oscillator to obtain more accurate intermediate frequency.

Design and optimization of strained-layer-multiquantum-well lasers for high-speed analog communications

Abstract: We report on how the contributions from spatial hole burning, gain suppression, and relaxation oscillations to the chirp and harmonic distortion of SL-MQW DFB lasers can be calculated and minimized. It is shown how, by taking into account the specific properties of strained-layer-multiquantum-well (SL-MQW) lasers, simple solutions of the rate equations point the way to a chirp reduction and an increase of the useful bandwidth for analog communications. In such lasers, the absorption is only weakly dependent on the carrier density and therefore the harmonic distortion at lower modulation frequencies is mainly caused by spatial hole burning. Our numerical simulations indicate that in many cases this distortion is seduced by the same measures that reduce the chirp and increase the bandwidth. >

A new approach to determine the start-up time of sinusoidal oscillators

Abstract: A transient waveform leaving the metastable equilibrium of a flipflop exhibits a very similar shape like the rising amplitude of an LC oscillator in the start-up phase. This paper is used to develop a new approach to determine the start-up behavior of nearly sinusoidal oscillators.

Chaos, torus and synchronization from three coupled relaxation oscillators

Abstract: This paper analyzes fundamental phenomena from three coupled relaxation oscillators. The system nonlinearity is a piecewise linear hysteresis comparator and we can explicitly calculate the return map and its Lyapunov exponents. Then we clarify generation of chaos, 2-torus, 3-torus and various kinds of synchronizations. Also, a rough bifurcation diagram is given. It indicates that 3-torus is popular for weak coupling and chaos is popular for relatively strong coupling. Some of the phenomena are confirmed by laboratory measurements. >

Disaster avoidance clock for anti-lock braking system

Abstract: On an integrated circuit (230), a back-up oscillator circuit (231) is provided which includes a back-up oscillator (540) which can be fabricated using conventional integrated circuit techniques, a clock monitor (520) for sensing a malfunction in a primary oscillator, and a multiplexer (530) for switching from the primary oscillator to the back-up oscillator (540) in the event the primary oscillator malfunctions. The back-up oscillator (540) is typically used in an anti-lock braking system to provide a safe shutdown after an oscillator malfunction. The internal back-up oscillator (540) being sufficient for execution of a shutdown routine.

Locally excitatory globally inhibitory oscillator networks: theory and application to pattern segmentation

Abstract: An novel class of locally excitatory, globally inhibitory oscillator networks (LEGION) is proposed and investigated analytically and by computer simulation. The model of each oscillator corresponds to a standard relaxation oscillator with two time scales. The network exhibits a mechanism of selective gating, whereby an oscillator jumping up to its active phase rapidly recruits the oscillators stimulated by the same pattern, while preventing other oscillators from jumping up. We show analytically that with the selective gating mechanism the network rapidly achieves both synchronization within blocks of oscillators that are stimulated by connected regions and desynchronization between different blocks. Computer simulations demonstrate LEGION's promising ability for segmenting multiple input patterns in real time. This model lays a physical foundation for the oscillatory correlation theory of feature binding, and may provide an effective computational framework for pattern segmentation and figure/ground segregation. >

Locally excitatory globally inhibitory oscillator networks: theory and application to pattern segmentation

Abstract: An novel class of locally excitatory, globally inhibitory oscillator networks (LEGION) is proposed and investigated analytically and by computer simulation. The model of each oscillator corresponds to a standard relaxation oscillator with two time scales. The network exhibits a mechanism of selective gating, whereby an oscillator jumping up to its active phase rapidly recruits the oscillators stimulated by the same pattern, while preventing other oscillators from jumping up. We show analytically that with the selective gating mechanism the network rapidly achieves both synchronization within blocks of oscillators that are stimulated by connected regions and desynchronization between different blocks. Computer simulations demonstrate LEGION's promising ability for segmenting multiple input patterns in real time. This model lays a physical foundation for the oscillatory correlation theory of feature binding, and may provide an effective computational framework for pattern segmentation and figure/ground segregation. >

Synchrony and Desynchrony in Neural Oscillator Networks

Abstract: An novel class of locally excitatory, globally inhibitory oscillator networks is proposed The model of each oscillator corresponds to a standard relaxation oscillator with two time scales The network exhibits a mechanism of selective gating, whereby an oscillator jumping up to its active phase rapidly recruits the oscillators stimulated by the same pattern, while preventing others from jumping up We show analytically that with the selective gating mechanism the network rapidly achieves both synchronization within blocks of oscillators that are stimulated by connected regions and desynchronization between different blocks Computer simulations demonstrate the network's promising ability for segmenting multiple input patterns in real time This model lays a physical foundation for the oscillatory correlation theory of feature binding, and may provide an effective computational framework for scene segmentation and figure/ground segregation

Switching driver overload protection circuit

Abstract: A circuit for protecting a field current transistor 28' for a generator, comprises means 182,184 for controlling current through the transistor, and a relaxation oscillator 180 for reducing the current in response to increasing load. The control may be a PWM gate drive signal. The oscillator changes the gate drive signal duty cycle in response to the load current. The oscillator 180 includes a comparator 190 operating with hysteresis.

Semiconductor integrated circuit with plural use of a terminal

Abstract: A semiconductor integrated circuit includes an oscillator circuit, which amplifies a signal sent from an oscillator by an amplifier circuit operating with a low power supply voltage for outputting the same. In the oscillator circuit, a threshold voltage of a transfer gate forming a switching element is set to a value lower than a threshold voltage of other transistors so as to reduce an on-resistance of the transfer gate and hence to ensure output of a signal supplied from said oscillator.

Variable frequency oscillator with feedback network coupled to amplifying network

Abstract: The invention concerns a variable-frequency oscillator circuit, intended in particular for tuners, in which the feedback network (100) for the oscillator amplifier (1) includes the following: a series circuit made up of two resonant-circuit inductors (6, 7) and a resonant-circuit capacitor (8) in parallel with which the series circuit of another resonant-circuit capacitor (15) with adjustable capacitance (18, 20, 22) is connected. Connected to the junction point (30) between the two inductors (6, 7) are switching means (9, 17, 21) by means of which the first resonant-circuit capacitor (8) and the resonant-circuit inductor (7) connected to it can be short-circuited under the control of a switching signal (S). The feedback network (100) can thus be switched between two frequency bands and is symmetrical with respect to the high-frequency effect.

Power oscillator design: class E

Abstract: An analytic approach to the design of high efficiency tuned power oscillator is presented By employing large-signal S-parameters, theoretical conditions for optimum operation of the oscillator have been formulated and discussed Loss due to non-zero switching time, saturation resistance etc of the transistor employed is accounted for Various oscillators at 900 MHz were designed using the derived theory Experimental results showed that the measured data are in good agreement with the predicted data >

Power supply system with a high power factor

Abstract: A power supply system with a high power factor is disclosed, which is distinguished by a high efficiency, small size and low weight, an input power factor being set to the value 1 and a resonant converter being driven, it being possible at the same time to minimise a high-frequency component of an AC supply voltage. The power supply system, according to the invention, with a high power factor has the following components: a full-wave rectifier device for rectifying an AC signal; a voltage divider device for dividing a rectified signal; a capacitor connected in parallel with the voltage divider device; an inductor connected to the full-wave rectifier device; a switching device to control the supply of the current flowing in the inductor; a resonant circuit section, formed from the inductor and the capacitor and connected to the switching device; an output circuit, which receives a signal from the resonant circuit section, rectifies the said signal and then transmits it to a load; and a control circuit, which supplies a switching control signal to the switching device. The control circuit has a sawtooth wave signal generator, a comparator device for comparing an output signal from the voltage divider device with a signal from the sawtooth wave signal generator, and a frequency divider for generating a ... Original abstract incomplete.

LOCALLY EXCITATORY GLOBALLY I NHl BlTORY OSCl LLATOR N ETWOR KS: THEORY AND APPLICATION TO PATTERN SEGMENTATION

Abstract: An novel class of locally excitatory, globally inhibitory oscillator networks (LEGION) is proposed and investigated analytically and by computer simulation The model of each oscillator corresponds to a standard relaxation oscillator with two time scales The network exhibits a mechanism of selective gating, whereby an oscillator jumping up to its active phase rapidly recruits the oscillators stimulated by the same pattern, while preventing other oscillators from jumping up We show analytically that with the selective gating mechanism the network rapidly achieves both synchronization within blocks of oscillators that are stimulated by connected regions and desynchronization between different blocks Computer simulations demonstrate LEGION'S promising ability for segmenting multiple input patterns in real time This model lays a physical foundation for the oscillatory correlation theory of feature binding, and may provide an effective computational framework for pattern segmentation and figure/ground segregation

A versatile monolithic 800 kHz to 800 MHz phase-startable oscillator

Abstract: A phase-startable voltage controlled oscillator is achieved that covers the frequency range of 800 kHz to 800 MHz using a modified multivibrator topology. The IC was fabricated on a recently developed highspeed complementary bipolar process (vertical NPN f/sub tau/=9 GHz and vertical PNP f/sub /spl tau//=5.5 GHz). The IC operates from /spl plusmn/5 volt supplies, and provides linearly adjustable frequency over a 500:1 range as well as a linearly adjustable period over a 4:1 range. The design exhibits an extremely short startup transient time of two cycles for steady-state oscillation while still providing moderate phase noise performance of -110 dBc/Hz at 1 MHz distance from the 400 MHz carrier. >