Voltage-controlled oscillator

About: Voltage-controlled oscillator is a research topic. Over the lifetime, 23896 publications have been published within this topic receiving 231875 citations. The topic is also known as: VCO.

Temperature telemetering apparatus

Abstract: Apparatus for providing, at a remote location, an indication of the temperature of a rotating body, such as the rotor of a centrifuge, comprising a closed loop feed-back circuit including a voltage controlled oscillator positioned remote from the rotor and a frequency sensitive bridge circuit mounted on the rotor. The bridge circuit includes a thermistor such that the balance frequency thereof is a function of the temperature of the rotor. The output of the voltage controlled oscillator is transmitted to the rotor where it excites the bridge circuit which generates an output signal whose amplitude is a function of the difference between the frequency of the oscillator and the balance frequency of the bridge circuit. The output signal from the bridge circuit is transmitted back to the remote location where it is applied, together with the output of the oscillator, to a phase sensitive detector which serves as an error detector to adjust the frequency of the voltage controlled oscillator to null the output of the bridge circuit. The output of the voltage controlled oscillator which is transmitted to the rotor is also used to energize a self-contained power supply thereby providing power for the rotor-mounted components. In addition, the output of the voltage controlled oscillator is modulated between two amplitude levels before transmission to the rotor-mounted components. When the oscillator output is high and the power supply on the rotor is drawing current, the detector is short-circuited. When the oscillator output is low and the power supply is discharging and not drawing current, the phase sensitive detector is operative.

Microwave apparatus for measuring fluid mixtures

Abstract: An apparatus for measuring the concentration of one material in another, such as the concentration of water in crude or refined mineral oil, comprises a conduit for receiving and discharging a continuous flow stream of the fluid mixture and which is formed as part of a coaxial microwave transmission line. A microwave or radio frequency range signal generator in the form of an unbuffered oscillator is connected to the transmission line for generating a high frequency signal which may be varied by a voltage controlled oscillator tuning circuit. A signal receiver monitors the change in frequency caused by impedance pulling of the oscillator due to the change in fluid dielectric constant and transmits a differential frequency signal to a frequency counter and microprocessor for comparison of the measured signal with known reference signals for determining the percentage of one fluid mixed in the other in the flow stream. The apparatus measurement section is adapted to provide for connecting standard microwave coaxial connectors to a relatively large diameter pipe or conduit comprising the coaxial transmission line portion of the measurement section.

Method and apparatus for synthesizing dual band high-frequency signals for wireless communications

Abstract: A method and apparatus for synthesizing high-frequency signals is disclosed that overcomes integration problem associated with prior implementations while meeting demanding phase noise and other impurity requirements. In one embodiment, a phase-locked loop (PLL) frequency synthesizer is disclosed having a voltage controlled oscillator (VCO) with a variable capacitance that includes a discretely variable capacitance in conjunction with a continuously variable capacitance. The discretely variable capacitance may provide coarse tuning adjustment of the variable capacitance, and the continuously variable capacitance may provide a fine tuning adjustment of the variable capacitance. In a further detail, wireless communication frequency synthesizer for generating multiple band high-frequency signals is disclosed having a first VCO selectable for a first frequency band and a second VCO selectable for a second frequency band.

Analysis of a neural oscillator

Abstract: Although the Matsuoka neural oscillator, which was originally proposed as a model of central pattern generators, has widely been used for various robots performing rhythmic movements, its characteristics are not clearly explained even now. This article shows two closed-form relations that express the frequency and amplitude of the generated oscillation as functions of the parameters of the model. Although they are derived based on a rough linear approximation, they accord with the result obtained by a simulation considerably. The obtained relations also give us some nontrivial predictions about the properties of the oscillator.

Analog open-loop VCO calibration method

Abstract: An analog open-loop voltage controlled oscillator (VCO) calibration circuit and method for selecting the frequency of the VCO for a phase locked loop (PLL). A frequency divider module produces a 50% duty cycle divided local oscillation and a 50% duty cycle divided reference signal, wherein the divided signals are substantially equal. A period-to-voltage conversion module converts the divided local oscillation signal and the divided reference signal to voltages proportional to the divided signals. A comparator module produces a frequency adjustment signal based on a comparison of the proportional voltages and couples the frequency adjustment signal to a logic module which produces a frequency compensation signal based on the frequency adjustment signal. The frequency compensation signal functions to adjust the configuration of switched capacitors in a capacitor bank, coupled to the VCO tuned circuit, until the divided local oscillation signal is substantially equal to the divided reference signal.