Relaxation oscillator

About: Relaxation oscillator is a research topic. Over the lifetime, 1952 publications have been published within this topic receiving 22326 citations.

A Resistance-to-Digital Converter possessing exceptional insensitivity to circuit parameters

Abstract: A new Resistance-to-Digital Converter (RDC) suitable for single element resistive sensors is presented in this paper. The proposed scheme is based on a relaxation oscillator circuit, which along with a timer-counter that measures the time intervals of oscillations, provides digital output proportional to the resistance of the sensor. In most of the existing RDCs, the output characteristic has gain, offset and non-linearity errors owing to various circuit parameters and their drift in the measurement unit. The output of the proposed RDC has a special nature, by the design of the measurement method, that it is not a function of the circuit parameters such as offset voltages and bias currents of the opamps and comparators used, gain of various units employed, ON-resistance of the switches, value or mismatch in the magnitudes of the reference voltages employed, etc. Such a scheme will be useful for high accuracy measurements, even in circumstances where the above-mentioned parameters may vary or drift, due to variation in the measurement environment, say, large variation in temperature. A prototype of the proposed RDC has been developed in the laboratory and the performance has been tested under various conditions. The output was found to be linear with a worst-case non-linearity of 0.06 % As expected, the sensitive of the output of the prototype RDC to various circuit parameters was found to be negligible.

Stable frequency oscillator having two capacitors that are alternately charged and discharged

Abstract: An oscillator circuit capable of being fully implemented in integrated circuit form and having a first current source for charging a first capacitor so as to produce a time varying voltage which is sensed by a first comparator when the voltage reaches a predetermined threshold level. The circuit further includes a second current source for charging a second capacitor so as to produce a further time varying voltage which is sensed by a second comparator when the voltage reaches the predetermined threshold voltage. The output of first and second comparators are combined so as to produce the output clock signal, with the first cycle segment of the clock having a duration determined by the first comparator output and the second cycle segment of the clock having a duration determined by the second comparator output.

Control of ultrasonic vibratory transducer - has phase comparator maintaining oscillator frequency equal to resonance frequency

Abstract: The transducer has a resonant circuit, and is controlled by a voltage or current controlled oscillator (3). A voltage is derived corresponding to the phase of the current supplied to the transducer. This voltage is applied to a phase comparator (1) as a first input signal, whose second input signal is the transducer driving voltage. The voltage or current controlled oscillator is controlled by the phase comparator output signal in accordance with the phase difference between its two input signals. This results in the transducer driver frequency being always equal to the resonance frequency.

Relaxation oscillator with low temperature drift characteristic, and debug method thereof

Abstract: The invention provides a relaxation oscillator with a low temperature drift characteristic and a debug method thereof, and relates to an oscillator field. The oscillator circuit comprises a bias module, a register and an oscillation module. The oscillation module is composed of a switching structural circuit, a comparator and a capacitor charging and discharging circuit. The oscillator uses switching structural circuit as a core, and a debug method of a current adjusting mode is combined, such that monolithic integration of the relaxation oscillator is realized while the oscillation frequency of the oscillator obtains excellent temperature stability. The disclosed switching structural circuit in the invention is provided for enable the relaxation oscillator to acquire the good temperature stability. According to a working principle of the circuit, the relaxation oscillator always possesses the good temperature stability no matter threshold voltages with different temperature characteristics are provided to the comparator by components in the switching structural circuit. The relaxation oscillator with the low temperature characteristic in the invention and the debug method thereof are suitable for any standard CMOS technologies.

Stabilized crystal controlled oscillator

Abstract: The invention relates to an oscillator having a positive feedback amplifier circuit the gain of which is controlled in direct opposite relationship to the amplitude of the oscillatory voltage produced by the oscillator and is especially useful for crystal controlled oscillators. The controlled feedback amplifier comprises a differential amplifier one branch of which feeds a rectifier producing the control voltage and the other branch of which acts as the controlled feedback amplifier.