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.

Unilateral coupling for a quadrature voltage controlled oscillator

Abstract: According to some embodiments, unilateral coupling is provided for a quadrature voltage controlled oscillator. For example, a first voltage controlled oscillator may be provided with a 0 degree phase node and a 180 degree phase node A second voltage controlled oscillator may be provided with a 90 degree phase node and a 270 degree phase node. In addition, the first and second voltage controlled oscillators may be mutually coupled with substantially unilateral cascaded common-source common-gate amplifier coupling devices to create a quadrature voltage controlled oscillator.

The Effect of Carrier Frequency Modulation of PWM Waveforms on Conducted EMC Problems in Switched Mode Power Supplies

Abstract: SummaryElectromagnetic compatibility (EMC) remains an issue which can present many problems to designers of high frequency power converter circuits. Usual techniques for alleviating the problems of interference generation by power converters involve the use of screening materials and filters, however, the effectiveness of such measures depends on the frequency the interference and the power density at each frequency of interest. As pulse width modulation (PWM) generates high frequency harmonics at multiples of the switching frequency, modulation of the switching frequency may be used to spread the spectral power density present at these harmonic frequencies. This paper presents a technique of frequency-hopping spread-spectrum modulation which may be applied to switched-mode power converters (SMPC’s) to reduce the spectral power density at harmonics of the switching frequency. The influence of the peak frequency deviation, the modulation sequence length and the type of modulating sequence on the resultant ...

Performance of internal-mirror frequency-stabilized He-Ne lasers emitting green, yellow or orange light

Abstract: A comprehensive control system has been developed for the stabilization of internalmirror He-Ne lasers to their power envelopes. It is designed particularly for use with lasers emitting at 552, 505, or 490 THz (543, 594, 612 nm). The aim has been to combine convenience in routine operation with good day-to-day resettability and minimal frequency drift during a day. The lasers are observed to emit in up to four modes simultaneously and their tuning behaviour is highly alignment-sensitive. They also tend to flip between modes having orthogonal linear planes of polarization. Reliable control of polarization and mode frequency are possible using permanent magnets and active length control through thermal expansion. The stabilized single-frequency outputs have frequency drifts of about 2×10−8 per year, and powers of between 150 μW and 850 μW.

Frequency stability measuring technique using digital signal processing

Abstract: To measure the frequency stability of an atomic oscillator having high-frequency stability, a technique using a pair of mixers and a time interval counter is widely used. This technique shares the signals of a local oscillator, uses a pair of mixers to convert the signals of the reference oscillator and the signals of the test oscillator to beat signals, and then uses a time interval counter to measure the phase difference between the beat signals. In this paper, the authors propose a frequency stability measuring technique that uses a two-channel audio band digitizer in place of the time interval counter. This technique uses the local oscillator and pair of mixers to convert the test signals and reference signals to audio-band beat signals, and then performs an analog-to-digital conversion on the beat signals. When the phase difference between two beat signals is numerically calculated, not only the effect of the local oscillator's phase noise can be eliminated, but the DC offset voltage generated from the mixers is not a critical problem for frequency stability measurements. The authors developed a prototype frequency stability analyzer based on this technique and obtained an Allan deviation (square root of the Allan variance) of σy(τ) = 5 × 10−17 at τ = 1000 seconds as a result of measuring its residual noise at a frequency of 100 MHz. This technique can be used to analyze a wide range of properties such as the clock quality of digital devices that operate at high speed, as well as the frequency stability of atomic oscillators at arbitrary nominal frequencies. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(1): 21–33, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10097

Bulk effect semiconductor oscillator including resonant low frequency input circuit

Abstract: The high frequency oscillator includes a body of n-type gallium arsenide which exhibits a bulk negative resistance when the field applied to the body exceeds a threshold field. The input circuit for theoscillator forms, with the gallium arsenide body, a circuit which is resonant at a frequency lower than the frequency of the output. An input signal is applied which causes the threshold field to be exceeded and high frequency output oscillations to be produced in the output circuit. The negative resistance then exhibited by the body causes the input voltage in the low frequency resonant circuit to oscillate reaching amplitudes in excess of the applied voltage and causing a high power output to be realized at the higher frequency.