Relaxation oscillator

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

Transcutaneous electrical nerve stimulator

Abstract: A transcutaneous electrical nerve stimulator in which a unijunction transistor relaxation oscillator is used to produce variable frequency, variable width pulses The relaxation oscillator drives a two stage transistor amplifier and the output therefrom is transformer coupled to a set of output electrodes which are adapted to be placed on the area of a patient to be treated The amplitude of the signals applied to the patient as well as the rate and duration thereof are controllable so that the patient may adjust the nerve stimulation to suit his particular needs

Isolation and transforming circuit

Abstract: A combination isolating and transforming circuit which consists primarily of three sections, a peak current limiting section and current and voltage isolation sections which electrically isolate the control circuit from the circuit being monitored. The input from the circuit to be measured, either from a bus bar or from a shunt resistor, drives an operational amplifier which controls a variable frequency oscillator. The pulses from this oscillator drive a single-shot multivibrator, the output of which is fed back to the operational amplifier as a negative feedback system. The operational amplifier, in turn, changes its output to adjust the frequency of the oscillator so that duty cycle of the output of the multivibrator has an on-off ratio as a function only of the input signal to the circuit. As this multivibrator switches positive and negative, the pulses are coupled through a pulse transformer to the non-isolated portion of the circuit. This latter circuit includes a flip flop which is driven to follow the multivibrator to produce the same duty-cycle signal in the output circuit as was generated in the circuit electrically connected to the load. The output circuit includes a second operational amplifier which scales and averages this duty-cycle signal and recreates a direct current signal proportional to the incoming voltage. The circuit thus results in a conversion from a voltage to a duty cycle and back to a voltage with very low drift.

Bifurcational mechanisms of synchronization of a resonant limit cycle on a two-dimensional torus

Abstract: We study synchronization of a resonant limit cycle on a two-dimensional torus with an external harmonic signal. The regime of the resonant limit cycle is realized in a system of two coupled Van der Pol oscillators; we consider the resonances 1:1 and 1:3. We analyze the influence of coupling strength between the oscillators. We show that the resonant limit cycle can be generally synchronized on the torus through the resonance destruction followed by the locking of one and then another one of the basic frequencies. We consider the bifurcational mechanism of the synchronization effect.

A pW-Power Hz-Range Oscillator Operating With a 0.3–1.8-V Unregulated Supply

Abstract: In this paper, a pW-power relaxation oscillator for sensor node applications is presented. The proposed oscillator operates over a wide supply voltage range from nominal down to deep sub-threshold and requires only a sub-pF capacitor for Hz-range output frequency. A true pW-power operation is enabled thanks to the adoption of an architecture leveraging transistor operation in super-cutoff, the elimination of voltage regulation, and current reference. Indeed, the oscillator can be powered directly from highly variable voltage sources (e.g., harvesters and batteries over their whole charge/discharge cycle). This is achieved thanks to the wide supply voltage range, the low voltage sensitivity of the output frequency and the current drawn from the supply. A test chip of the proposed oscillator in 180 nm exhibits a nominal frequency of approximately 4 Hz, a supply voltage range from 1.8 V down to 0.3 V with 10%/V supply sensitivity, 8–18-pA current absorption, and 4%/°C thermal drift from -20 °C to 40 °C at an area of $1600~\mu \mathrm {m}^{2}$ . To the best of the authors’ knowledge, the proposed oscillator is the only one able to operate from sub-threshold to nominal voltage.

Linearization of voltage-controlled oscillators using switched capacitor feedback

Abstract: The voltage-frequency characteristics of any voltage-controlled oscillator can be linearized using a simple circuit containing a switched capacitor The oscillation frequency becomes insensitive to power supply or temperature variations, and is determined only by the values of a capacitor, resistor, and the control voltage with respect to a reference voltage