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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
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Journal ArticleDOI
TL;DR: In this article, a multiply-by-three circuit with two 180/spl deg/-coupled single-ended three-stage ring oscillators has been fabricated in 0.24/spl mu/m CMOS, designed to work in the 902-928-MHz ISM band.
Abstract: A frequency-synthesis technique which extracts the Nth harmonic from an N-stage oscillator is presented. This technique enables significant power savings in the prescaler of a frequency synthesizer. The maximum achievable voltage swing from such an oscillator is estimated. To study this technique, a multiply-by-3 circuit with two 180/spl deg/-coupled single-ended three-stage ring oscillators has been fabricated in 0.24-/spl mu/m CMOS, designed to work in the 902-928-MHz ISM band (U.S. and Canada). It provides two outputs: one at the normal operating frequency of the oscillator and the other at three times that frequency. The circuit can work at voltages as low as 1.3 V, while consuming 210 /spl mu/A of current.

28 citations

Patent
08 Jun 1977
TL;DR: In this paper, a heterodyne phase lock system is disclosed having a plurality of oscillator circuits, at least one of the oscillator circuit being a voltage controlled oscillator (VCO) circuit, and the control circuit includes a phase lock circuit, which is responsive to an applied reference signal for adjusting the output of the VCO.
Abstract: A heterodyne phase lock system is disclosed having a plurality of oscillator circuits, a similar plurality of heterodyne (mixer-filter) circuits representing an input circuit, and a similar plurality of heterodyne circuits representing a control circuit, at least one of the oscillator circuits being a voltage controlled oscillator (VCO) circuit. The heterodyne circuits of the input circuit are cascaded, i.e., linked each to the other, successively, and the heterodyne circuits of the control circuit are likewise cascaded. Each oscillator is linked to a pair of heterodyne circuits, i.e., to one heterodyne circuit in the input circuit and to one heterodyne circuit in the control circuit, and applies a common output signal to said pair of heterodyne circuits. The control circuit includes a phase lock circuit, and is responsive to an applied reference signal for adjusting the output of the VCO and correcting for or substantially cancelling frequency drift, residual FM, and phase noise introduced into the system by the oscillators. This manner of linking oscillators to both heterodyne input and control circuits in a system so as to be able to correct, by adjusting a single oscillator, for frequency drift, residual FM, and phase noise from all of the oscillators in the system, is applicable to receiver and generator type systems alike. The system also includes an offset oscillator for tuning the system.

27 citations

Patent
23 Sep 2002
TL;DR: In this article, a received signal transformer removes from a training symbol a guardtone and a sub-carrier deviated from a mean value of effective subcarrier signals by over a predetermined value.
Abstract: In an orthogonal frequency division multiplexing (OFDM) system, a receiver includes a received signal transformer, a frequency offset estimator and a frequency compensator. The received signal transformer removes from a training symbol a guardtone and a sub-carrier deviated from a mean value of effective sub-carrier signals by over a predetermined value. The frequency offset estimator estimates the frequency offset of the OFDM digital signal and the frequency compensator compensates the frequency offset of received signals by using the estimated frequency offset. Thus, data transmission efficiency can be greatly improved and influence from a frequency-selective noise channel can be minimized. Further, by removing data unnecessary for the frequency offset estimation, the calculation amount can be reduced.

27 citations

Patent
11 Feb 2016
TL;DR: In this article, a phase-locked loop with a feedback path, a time-to-digital converter, and a memory is described, where the memory stores second control input values that each correspond with a desired chirp frequency and which compensate for nonlinearity in the response of the frequency controlled oscillator to the second input.
Abstract: A phase locked loop is disclosed having a frequency controlled oscillator, a feedback path, a time to digital converter and a memory. The frequency controlled oscillator comprises a first control input for varying the frequency of the output of the frequency controlled oscillator so as to track a reference frequency and a second control input for modulating the frequency of the output signal so as to produce a chirp. The feedback path is configured to provide an input signal to the time to digital converter, and comprises modulation cancelling module operable to remove the frequency modulation resulting from the second control input from the output signal. The memory stores second control input values that each correspond with a desired chirp frequency and which compensate for non-linearity in the response of the frequency controlled oscillator to the second control input. The phase locked loop is operable in a chirp mode, in which the second control input is produced by determining a value for the second control input corresponding with a desired chirp frequency based on the stored second control input values in the memory, and in which the phase locked loop is configured to determine the first control input based on the feedback path from which the modulation cancelling module has removed the frequency modulation resulting from the second control input.

27 citations

Patent
27 Mar 2002
TL;DR: In this article, single-sideband mixers are used to produce output signals at the sum of the VCO frequency and the shifted frequency while suppressing an unwanted sideband at the difference of the two frequencies.
Abstract: A local oscillator architecture provides a signal at an output frequency with reduced pulling effect. A voltage controlled oscillator (VCO) generates a first signal having a frequency that is a fraction of the output frequency. A frequency shifter generates a second signal with a frequency substantially equal to the difference between the VCO frequency and the output frequency. Single-sideband mixers are used to produce output signals at the sum of the VCO frequency and the shifted frequency while suppressing an unwanted sideband at the difference of the two frequencies.

27 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202217
202150
202059
201963
201887