Relaxation oscillator

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

Pseudo voltage controlled oscillator

Abstract: For use in a VLG navigation system, such as the Omega Navigation system, a phase tracking loop in a receiver receives incoming signals from transmitting stations. The tracking loop contains four electronically controlled pseudo voltage-controlled oscillators, to eliminate the need for all but one master crystal oscillator, whose outputs provide necessary signals within the receiver. The pseudo oscillator comprises an integrator and a voltage-to-phase converter using an external clock pulse input and suitable control logic. The voltage-to-phase converter comprises a one-shot multivibrator in which the delay time is proportional to the input signal level. Thus, the periods between return times of the one-shot multivibrator to its original state provide a frequency which is controlled by input voltage level. When the phase-shift range exceeds + OR - 90* , the trigger pulse to the one-shot multivibrator is advanced or delayed, and the integrator is reset to zero.

An inexpensive solar pointing control

Abstract: The theory, design and performance of an inexpensive, biaxial solar pointing control are presented and discussed. An altazimuth mount driven by fractional horsepower d.c. motors is used as the stable platform. Two identical error-sensing circuits are employed to drive the motors. A dual element photoconductive cell is used as the sensor in each circuit. The two elements form the variable arms of a simple a.c. bridge which is balanced when the two elements are equally illuminated. This condition prevails when the sensor is pointing at the sun. The off-balance voltage which results when the two are unequally illuminated is used to forward-bias the emitter junction of a unijunction transistor in a relaxation oscillator circuit which triggers a silicon controlled rectifier switching circuit. This circuit changes the polarity of the supply voltage to the d.c. motor which positions the altazimuth mount to restore the balance. Tracking accuracies of ?0? 30' of arc both in elevation and azimuth are easily attainable with loads up to 30 1b.

A pseudo differential G m —C complex filter with frequency tuning for IEEE802.15.4 applications

Abstract: This paper presents a CMOS Gm—C complex filter for a low-IF receiver of the IEEE 802.15.4 standard. A pseudo differential OTA with reconfigurable common mode feedback and common mode feed-forward is proposed as well as the frequency tuning method based on a relaxation oscillator. A detailed analysis of non-ideality of the OTA and the frequency tuning method is elaborated. The analysis and measurement results have shown that the center frequency of the complex filter could be tuned accurately. The chip was fabricated in a standard 0.35 μm CMOS process, with a single 3.3 V power supply. The filter consumes 2.1mA current, has a measured in-band group delay ripple of less than 0.16 μs and an IRR larger than 28 dB at 2 MHz apart, which could meet the requirements oftheIEEE802.15.4 standard.

Phase-locking loop with variable bandwidth filter

Abstract: A phase-locking network at the receiving end of a transmission channel carries an incoming wave of predetermined frequency matching the operating frequency of a local oscillator the incoming wave and the locally generated oscillations being fed to respective inputs of a phase comparator producing a control voltage delivered through a low-pass filter to the oscillator for reducing any existing phase difference. The signal path between the phase comparator and the oscillator includes one or more nonlinear impedance elements, either within the filter or in cascade therewith, which lowers the effective series resistance of the path in the presence of a high control voltage and thereby increases its bandwidth during an acquisition period as compared with steady-state operation.

A Wide Range Voltage-Controlled Oscillator

Abstract: An understanding of the fundamental constraints which limit the performance of controlled oscillators has permitted the development of a VCO having exceptional performance. The output frequency is relatively independent of power supply and temperature and is proportional to the controlling voltage for at least four decades. The switching circuitry is operated in a nonsaturating mode which allows frequency operation to 5 MHz. The entire circuit is compatible with monolithic IC technology.