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.

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

Abstract: A frequency synthesizer is provided with a prescaler 2 and a counter 3, which output a signal having a frequency generated by frequency-dividing an output signal of a VCO 1; a reference frequency divider 5 for frequency-dividing a frequency of a reference signal of a reference signal source 4; a frequency adjusting meas 9 operated in such that a frequency error between the output signal of the counter 5 and the output signal of the reference frequency divider 5 is detected, and in response to this detection result, such a signal is outputted by which either a capacitor value or an inductor value employed in a resonant circuit of the VCO 1 is switched; and also a bias control means for applying an arbitrary voltage V1 to a control voltage terminal of the VCO 1 so as to bring an output signal of a charge pump 7 into a high impedance state when the frequency adjusting means 9 is operated. Since the resonant frequency of the resonant circuit is changed in response to an actual oscillation frequency of the VCO 1, the frequency synthesizer can be phase-locked at a desirable frequency. Also, since the VCO can be manufactured in the IC form, the compact VCO can be made in low cost.

A Fractional-N Divider-Less Phase-Locked Loop With a Subsampling Phase Detector

Abstract: A low-noise divider-less PLL, employing a subsampling locked loop, samples the VCO output by a digital pulse-width modulator (DPWM) to perform fractional-N operation. The frequency synthesizer achieves a low in-band phase noise of -112 dBc/Hz at a 2.3 GHz output frequency. The analysis for the frequency synthesizer, especially for the nonlinear characteristics of the circuits, is proposed. Fabricated in a 0.18 μm CMOS technology, the frequency synthesizer consumes 9.6 mA and achieves figure-of-merit of -239.1 dB, corresponding to 266 fs rms jitter.

Phase locked loop circuit

Abstract: PURPOSE:To obtain the phase locked loop circuit, for which pull-in is made easy even when mixing disturbance noise, by providing a means to suppress gain small at a phase comparator when a frequency component higher than a predictive frequency component is included in an external input. CONSTITUTION:When the mixture of disturbance noise is detected or estimated, the gain at a phase comparator 1 is suppressed small regardless of the function of a mode controller 4. Therefore, the output frequency of a voltage controlled oscillator does not exceed the pull-in limit because of the disturbance noise and when a frequency fi within the pull-in limit is inputted in place of the disturbance noise, pull-in is enabled. Thus, even when inputting the disturbance noise of the high frequency component to the phase comparator 1 which gain can be controlled to be increased/decreased, pull-in can be easily executed after the input.

Ink jet recorder

Abstract: PURPOSE:To make the printing density adjustable by mounting a means for variably controlling the oscillating frequency of an oscillator, a means for modulating the pulse width of a printing signal according to the change in oscillating frequency of the oscillator, and a printing means for changing the travel speed at the printing position CONSTITUTION:An oscillator mounted on a nozzle is driven by a VCO(voltage control oscillator) 29 The oscillating frequency of the VCO 29 is varied by a variable resistance 28 In an F/V(frequency-voltage) converter 31, a motor 23 is driven in accordance with the oscillating frequency of the VCO 29, a rotating drum 21 is rotated, and recording paper 22 is fed in accordance with an interval of ink drop separation A CPU 27 inputs the output of the VCO 29 and the output of an encoder 24 detecting the rotating state of a rotating drum 21 and outputs a printing signal after changing the pulse width thereof On this output, a high voltage driver 30 drives a charged electrode on a head part 20, and the head part 20 is driven in accordance with the output of the VCO 29 In this manner, printing density can be adjusted simply by adjusting the variable resistance 28 while observing an image to be printed

Extremely Coherent Microwave Emission from Spin Torque Oscillator Stabilized by Phase Locked Loop.

Abstract: Spin torque oscillator (STO) has been attracting a great deal of attention as a candidate for the next generation microwave signal sources for various modern electronics systems since its advent. However, the phase noise of STOs under free running oscillation is still too large to be used in practical microwave applications, thus an industrially viable means to stabilize its oscillation has been strongly sought. Here we demonstrate implementation of a phase locked loop using a STO as a voltage controlled oscillator (VCO) that generates a 7.344 GHz microwave signal stabilized by a 153 MHz reference signal. Spectrum measurement showed successful phase locking of the microwave signal to the reference signal, characterized by an extremely narrow oscillation peak with a linewidth of less than the measurement limit of 1 Hz. This demonstration should be a major breakthrough toward various practical applications of STOs.