Topic
Frequency drift
About: Frequency drift is a research topic. Over the lifetime, 5054 publications have been published within this topic receiving 56191 citations. The topic is also known as: chirp rate.
Papers published on a yearly basis
Papers
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07 Nov 2007TL;DR: In this paper, a charge pump circuit includes a voltage controlled oscillator, which operates at a lower frequency during warm-up mode, and at a higher frequency during a loading mode, to reduce power supply current requirements.
Abstract: A charge pump circuit includes a voltage controlled oscillator The voltage controlled oscillator operates at a lower frequency during a warm-up mode, and operates at a higher frequency during a loading mode The lower frequency operation during the warm-up mode reduces power supply current requirements
26 citations
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TL;DR: The usefulness of frequency tuning is demonstrated by comparing images at different optimal combinations of driving frequency and bias voltage, acquired by linearly moving the transducer across a tissue mimicking phantom.
26 citations
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28 Feb 1991TL;DR: In this paper, an RF oscillator is described that can be tuned to operate over a wide range of frequencies while maintaining advantageous bias conditions without resorting to using the same signal for both bias and frequency control.
Abstract: An RF oscillator is disclosed that can be tuned to operate over a wide range of frequencies while maintaining advantageous bias conditions. The oscillator includes circuitry that adjusts an oscillator bias signal in response to changes in oscillator frequency and/or ambient temperature, and does so without resort to using the same signal for both bias and frequency control. By so doing to control parameters such as phase noise, output power and compression angle, both the frequency range and temperature range of an oscillator can be extended, while simultaneously improving the oscillator's performance.
26 citations
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09 May 2008TL;DR: In this paper, a method and apparatus for estimating oscillator signal variation due to temperature and for providing an estimated frequency to a GPS receiver in order to assist the GPS receiver to acquire the signals quickly is disclosed.
Abstract: A method and apparatus for estimating oscillator signal variation due to temperature and for providing an estimated frequency to a GPS receiver in order to assist the GPS receiver to acquire the signals quickly is disclosed. A temperature sensor is closely thermally coupled with the crystal oscillator in the GPS receiver and during GPS tracking mode, when the error in the oscillator signal is known with precision, outer bounds of TCXO frequency at given temperatures are maintained, which may correspond to rising and falling temperature conditions. During acquisition mode, an estimated frequency value is provided to the GPS receiver based on a determined average of these bounds. Optionally, an uncertainty factor associated with the frequency estimated may also be provided. The two bounds take into account the hysteresis effects of the oscillator signal drift due to temperature so that a more accurate initial frequency estimate can be provided to the GPS receiver, thus reducing its average time to first fix.
26 citations
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24 May 1982TL;DR: In this article, the relationship between the magnitude of the control signal and the frequency of the oscillator signal can be adjusted while avoiding mechanically adjustable reactive elements, and the disclosed arrangement is suitably employed with resonant circuits other than those in oscillators.
Abstract: A tunable oscillator develops a signal having a frequency variable over a range of frequencies in response to a control signal. A frequency determining resonant circuit includes two voltage-variable capacitance diodes in an arrangement for adjusting at least one endpoint of the frequency range. As a result, the relationship between the magnitude of the control signal and the frequency of the oscillator signal can be adjusted while avoiding mechanically adjustable reactive elements. The disclosed arrangement is suitably employed with resonant circuits other than those in oscillators.
26 citations