Topic
Relaxation oscillator
About: Relaxation oscillator is a research topic. Over the lifetime, 1952 publications have been published within this topic receiving 22326 citations.
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Papers
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30 Apr 1999TL;DR: In this paper, the slope-fixing circuit comprises a fixed timing capacitor C 1 in parallel with a plurality of switchable timing capacitors C 2... C N to provide an effective capacitance C. The slope of the control signal is determined by the ratio of a control current I to the effective capacitive C.
Abstract: An oscillator has a slope-fixing circuit that generates a control signal and fixes the slope of the control signal, a swing-fixing circuit that fixes the swing of the control signal, and a switching block that generates an output signal having a frequency derived from the swing and the slope of the control signal. The slope-fixing circuit comprises a fixed timing capacitor C 1 in parallel with a plurality of switchable timing capacitors C 2 . . . C N to provide an effective capacitance C. The slope of the control signal is determined by the ratio of a control current I to the effective capacitance C. The swing-fixing circuit comprises a replica cell that accepts a programmable reference voltage V REF and provides a fixed voltage swing V SW =V DD −V REF across a pair of load transistors. The switching block comprises a pair of switching transistors that alternate between “on” and “off” states depending on the value of the control signal to produce an oscillating output signal. The frequency of the output signal is given by I 4 CV SW .
27 citations
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TL;DR: The circuit which offers the minimum parasitic earth capacitance effect has the potential for accurately monitoring measurement parameters, particularly ppm-level humidity, and its application to a thin-film-based humidity sensor is reported.
Abstract: A simple signal conditioning circuit using a transformer ratio arm (TRA) bridge for converting capacitance change into frequency for capacitive sensors is presented. The circuit employs a relaxation oscillator in which the output frequency is linearly related to the capacitive unbalance of a TRA bridge. The design, analysis, and experimental results of the circuit and its application to a thin-film-based humidity sensor are reported. The experimental results confirm the theoretical value predicted. The circuit which offers the minimum parasitic earth capacitance effect has the potential for accurately monitoring measurement parameters, particularly ppm-level humidity. The simulation results for the effect of parasitic earth capacitances and ambient temperature on the output frequency have also been discussed. The pulse wave output of the circuit is interfaced with microcontroller for direct moisture display in ppm. The frequency sensitivity and nonlinearity of the sensor for the 0–110-ppm moisture range are found to be 10.94 Hz/ppm and 1.2%, respectively.
27 citations
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TL;DR: In this paper, the dependence of relaxation oscillation on carrier diffusion length in AlGaAs lasers is analyzed using multimode rate equations containing carrier diffusion and spontaneous emission terms, and a parameter representing coupling between carrier and light field distribution is introduced.
Abstract: The dependence of relaxation oscillation on carrier diffusion length in AlGaAs lasers is analyzed using multimode rate equations containing carrier diffusion and spontaneous emission terms. A parameter representing coupling between carrier and light field distribution is introduced. The carrier diffusion shortens the delay time, the relaxation oscillation period, and the decay time constant and also makes spectral narrowing faster. The damping factor is enlarged and relaxation oscillation is suppressed as the carrier diffusion length becomes large. The diffusion length, normalized by stripe width L D /W, is estimated to be about 0.6 by comparing the numerical results with the experimental tendency of transient response. Furthermore, relaxation oscillation is suppressed as the oscillation beam spot size becomes smaller.
26 citations
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TL;DR: In this paper, the frequency and damping of DFL relaxation oscillations are calculated using approximate solutions for over-coupled ( KL > 1) distributed feedback lasers above threshold and a small-signal perturbation analysis.
26 citations
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30 Nov 2009TL;DR: In this paper, the authors proposed a relaxation oscillator with a capacitor connected to a comparator input, current sources switched to supply power to the capacitor based on an output of the comparator, and a duplicate integrator shifting a voltage on the capacitor to offset a propagation delay through the comparators.
Abstract: A relaxation oscillator includes a capacitor connected to a comparator input, current sources switched to supply power to the capacitor based on an output of the comparator, and a duplicate integrator shifting a voltage on the capacitor to offset a propagation delay through the comparator. The duplicate integrator includes current sources and a capacitor matching and switched in tandem with those within the relaxation oscillator, plus an additional current source, and is selectively switched into connection with the comparator input. By canceling the comparator propagation delay, the oscillator output frequency can be stably controlled through selection of resistive and capacitive values, using cheaper technology and tolerating large temperature, voltage and process variations.
26 citations