Topic
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.
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Papers
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30 Jan 2002
TL;DR: In this paper, a capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object is described.
Abstract: A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object includes at least two sense electrodes (14,16) disposed on a surface and a phase locked loop (12), including a voltage controlled oscillator (22) and a phase/frequency comparator (24), connected between the sense electrodes and an RC network (20) for providing an operating frequency to the sense electrodes. A circuit loop, including a reference oscillator (32), provides a fixed frequency references for the phase locked loop to follow and a phase delay circuit (34) connected between the phase/frequency comparator and the voltage controlled oscillator causes the voltage controlled oscillation to run ahead of the reference oscillator. A trigger circuit (30) provides a control output in response to a change in phase shift between the fixed frequency and the operating frequency.
73 citations
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TL;DR: In this paper, an analytical model is presented to determine the VCO design parameters and the associated SET vulnerability, and radiation-hardened-by-design (RHBD) techniques to mitigate SETs in current-starved VCOs are presented.
Abstract: Voltage-controlled oscillators (VCOs) have been shown to dominate the single-event transient (SET) response of mixed-signal circuits such as the phase-locked loop (PLL). An analytical model is presented to determine the VCO design parameters and the associated SET vulnerability. Additionally, radiation-hardened-by-design (RHBD) techniques to mitigate SETs in current-starved VCOs are presented. The proposed mitigation techniques reduce the phase displacement in the output of the VCO following a single-event (SE) by approximately 66%. The availability of the analytical model and RHBD techniques will improve the SE performance of VCO and PLL designs to ensure a specified tolerance to SEs.
73 citations
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18 Mar 2010
TL;DR: This work presents an alternative technique that does not rely on resonant elements and does not affect both start-up margin and 1/f2 phase noise.
Abstract: Flicker noise up-conversion in voltage-biased oscillators can be effectively suppressed by inserting resistances in series to the drain of the transconductor MOSFETs. This solution avoids the degradation of the start-up margin and the adoption of area-demanding resonant filters with proper tuning. This paper presents a detailed theoretical analysis of 1/f noise up-conversion and quantitatively addresses the impact of two major contributions, namely the Groszkowski effect and the loop delay caused by stray capacitances at the drain node of the transistors. A simple flow for the design of an oscillator with suppressed flicker noise up-conversion is presented which is based on first-order closed-form formulas. Finally , theoretical estimates are compared to experimental results on a 65-nm CMOS VCO covering the 3.0-3.6 GHz band.
73 citations
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10 Feb 1992TL;DR: In this paper, a phase detector and a delay line discriminator are used to stabilize an oscillator having an output signal, and an adjustable phase shifter is controlled by a tuning microprocessor responsive to an externally controlled change in the frequency at which the oscillator is to be stabilized.
Abstract: A circuit for stabilizing an oscillator having an oscillator output signal includes a long optical fiber delay line which receives an optical version of the oscillator output signal and a phase detector sensing the oscillator output signal and the delayed optical output signal through the long optical fiber. The output of the phase detector is fed back to the oscillator's frequency control input to stabilize the frequency. The phase detector and the delay line are a delay line discriminator, and the length of the optical fiber is selected so as to optimize the discriminator's sensitivity against signal attenuation in the optical fiber, the optical fiber length typically being on the order of 10 kilometers. An adjustable phase shifter which maintains phase quadrature at the phase detector inputs at equilibrium is controlled by a tuning microprocessor responsive to an externally controlled change in the frequency at which the oscillator is to be stabilized, so as to follow changes in the selected oscillator frequency. As a result, an oscillator may be tuned in the circuit of the invention to any frequency in the general range of D.C. to optical frequencies.
73 citations
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05 Feb 1997
TL;DR: In this article, a method and system for calibrating a batch of devices each containing a circuit which is responsive to a control signal for producing a desired output which varies in accordance with a first predetermined function of a specific ambient condition, the second function being based on data stored as a look-up table in a memory of the device and which must be individually calibrated for each device.
Abstract: A method and system are provided for calibrating a batch of devices each containing a circuit which is responsive to a control signal for producing a desired output which varies in accordance with a first predetermined function of a specific ambient condition, the control signal having a magnitude which varies as a second predetermined function of the specific ambient condition, the second function being based on data stored as a look-up table in a memory of the device and which must be individually calibrated for each device. In a preferred embodiment, the device is a digital temperature controlled crystal oscillator which produces a desired output frequency and includes a voltage controlled oscillator (VCO) responsive to a control signal having a magnitude which varies as a predetermined function of ambient temperature in order to compensate for temperature variations in the oscillator output frequency. For such an application, the invention requires the connection of an accurate frequency source to each oscillator in the batch so as to enable the output frequency of the oscillator to be equalized thereto or to a multiple thereof. In calibration mode, the digital equivalent of the resulting analog control voltage is stored; whilst in compensation mode it is extracted from the memory, converted to an equivalent analog voltage and applied to the VCO. The invention is also applicable to compensate for aging of crystal oscillators in the field without requiring reconfiguring the complete look-up table.
73 citations