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.

The investigation of W-band solid-state frequency sources

Abstract: In this paper, the investigation of W-band solid-state continuous wave (CW) frequency sources is given, according to the types, such as HFET oscillator, Gunn diode oscillator, IMPATT oscillator and all kinds of frequency multiplier sources. The emphases are on the phase noise and frequency stability of frequency sources. Two W-band multiplier sources are developed, with spurious output less than -65dBc and phase noise -97dBc/Hz at 10kHz offset.

Digital communications receiver and method of estimating residual carrier frequency offset in a received signal

Abstract: A carrier frequency offset can be present in a signal received by a communications receiver, when the receiver has a local frequency oscillator that generates a carrier frequency different from a carrier frequency generated by a local frequency oscillator at a transmitter that transmitted the signal. A residual carrier frequency offset can remain after most of the carrier frequency offset has been removed from the received signal using conventional techniques. The residual carrier frequency offset is estimated using first and second channel impulse responses derived from first and second portions of the received signal. An estimated phase difference between the first and second channel impulse responses is computed. An estimate of the residual carrier frequency offset is computed using the estimated phase difference.

Fast AFC technique using a code estimation and binary search algorithm for wideband frequency synthesis

Abstract: This paper presents some skills to improve locking property in wideband frequency synthesizers. To support a wide frequency range with a single on-chip voltage controlled oscillator (VCO) without deteriorating lock time, we introduce an adaptive frequency calibration (AFC) technique, which is using a code estimation and binary search algorithm to reduce the number of comparisons in AFC mode. In addition, by varying the threshold frequency, which is a criterion to discriminate one AFC code from others, in accordance with the requested VCO output frequency, the unnecessary transition time can be reduced during phase-locked loop (PLL) settling mode. A fractional-N frequency synthesizer with an on-chip LC VCO was implemented in 0.18-/spl mu/m CMOS technology to verify the performance. The measurement results showed less than 35-/spl mu/s AFC time with 5-bit AFC, and total lock time was found to be less than 65-/spl mu/s with 30 KHz PLL loop bandwidth. The frequency range was more than 400 MHz.

Method of eliminating temperature induced band switching in ultra wideband voltage controlled oscillator

Abstract: A method and a voltage-controlled oscillator provide an output signal with a frequency within one of a plurality of frequency bands, while reducing or eliminating temperature-induced band-switching or other drifts in operating frequency. The band-switching is reduced or eliminated by providing a circuit that adjusts a tuning sensitivity according to a calibration performed under test conditions. For example, such a voltage-controlled oscillator may include (a) a digitally controlled variable current source for providing a first control current to select one of the frequency bands for the voltage-controlled oscillator; (b) a variable transconductance circuit providing a second control current to compensate a variation in operating frequency; and (c) a control circuit for varying the frequency of the output signal in accordance with the first and second control signals. The variable transconductance circuit may be programmable by selectively activating elements of an array of varactor circuits, according to a capacitance associated with each varactor circuit. The capacitance associated with each varactor circuit is binary weighted.

Power supply having automatic frequency control for ultrasonic bonding

Abstract: A power supply is provided for an electromechanical device of the type employing ultrasonic frequency vibratory energy for bonding materials. An automatic frequency control varies the output frequency of the power supply until the ratio of the maximum to minimum amplitudes of a standing wave produced in the mechanical vibratory member falls below a pre-set maximum. The frequency of the power supply is set by a voltage controlled variable frequency oscillator. A sweep generator produces a periodic voltage signal having a frequency substantially less than the frequency range of the voltage controlled oscillator. Means are provided for coupling the voltage signal from the sweep generator to the control input of the voltage controlled oscillator whenever the standing wave ratio exceeds a pre-set value, and for holding the last voltage signal received by the control input of the voltage controlled oscillator whenever the standing wave ratio is equal to or less than the pre-set value. Thus, the power supply frequency will be automatically varied to maintain the standing wave ratio below a pre-set value which is deemed to be an acceptable value for efficient transfer of power.