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.

Wide-band/multi-band voltage controlled oscillator

Abstract: A variable frequency signal generator, in the form of a voltage controlled oscillator, provides wide-band and/or multi-band output frequency operation using two control voltage inputs. A pair of LC oscillator circuits are cross-coupled through a transconductance control circuit. The oscillator circuits provide quadrature output frequency signals. The oscillator circuits include MOSFET varactors controllable by a first control voltage which can be used to drive the varactors into inversion or depletion operating modes which correspond to respective output signal frequency bands. A second control voltage is provided to the transconductance control circuit to control currents injected from each oscillator to the other, thereby selecting a particular output frequency within the range of the frequency band determined by the first control voltage. A control voltage compensation circuit is included to prevent variations in the second control voltage from altering the frequency band range selected by the first control voltage. Output signals with frequencies in the range 850 MHz to 2.4 GHz with favorable harmonic content and low phase noise are possible with relatively low supply voltages.

Thermally stable oscillator at 2.5 GHz using temperature compensated BAW resonator and its integrated temperature sensor

Abstract: This paper presents a miniaturized 2.5GHz frequency source based on compensated BAW resonator with its integrated temperature molybdenum sensor assembled on the differential Colpitts oscillator. The presence of silicon dioxide layer having a positive temperature coefficient compared to other layers is used to reduce the resonator's drift. A demonstration oscillator achieves a frequency drift of 40 ppm over a temperature range from -35degC to +85degC. The oscillator's phase noise of -94dBc/Hz at 2 KHz offset from the carrier is reported.

Frequency modulation of a millimeter-wave IMPATT diode oscillator and related harmonic generation effects

Abstract: In this paper we report the performance of a continuous wave millimeter-wave IMPATT diode oscillator with a wide-band tunability. The diode is mounted in an iris wafer circuit; its oscillation frequency can be modulated either by a varactor diode or by direct modulation of the IMPATT diode bias current. The oscillator has been successfully used as a millimeter-wave frequency deviator in an experimental pulse code modulation millimeter-wave system. We also report detailed measurements on subharmonic frequencies in IMPATT diode oscillators. Experimental results show that wide frequency tunability can be obtained with a circuit which provides an “idler” resonance at one-half the fundamental transit-time frequency. The results also show that by providing “idler” resonances at both the transit-time frequency and at one-half of the transit-time, the oscillation at 3/2 the transit-time frequency is enhanced and yields a useful output power of 2 mW at 86 GHz.

Joint position and carrier frequency estimation method of initial frequency acquisition for a WCDMA mobile terminal

Abstract: A WCDMA system and method of data communication allows a receiver to reliably achieve carrier frequency acquisition following turn-on without use of temperature compensation. Initial frequency acquisition is achieved by estimating the signal path position having the largest magnitude and then by estimating the phase difference associated with primary synchronization channels at a predetermined position within a single frame. The estimated phase difference is used to estimate a carrier frequency offset that can be used to adjust the local voltage controlled oscillator frequency, thereby acquiring the WCDMA communication signal carrier frequency.

Frequency synchronizing system for satellite communication

Abstract: A frequency synchronizing system for satellite communication, in which a reference frequency coming from a communications satellite is received by a receiving circuit. A first frequency variable oscillator is provided for generating a transmission signal. A second receiving circuit is provided for receiving through the communications satellite the transmission signal which is the output from the first frequency variable oscillator, A first frequency control circuit is provided for controlling the first frequency variable oscillator for making the frequencies of the outputs from the first and second receiving circuits equal to each other. A second frequency variable oscillator is provided for generating a signal of a frequency twice as high as the reference frequency. A frequency converter is provided for mixing the output from the first or second receiving circuit with the output from the second frequency variable oscillator to produce a signal of a difference frequency substantially equal to that of the transmission signal. A phase detector detects the phase difference between the transmission signal and the output from the frequency converter. A frequency control circuit is provided for controlling the second frequency variable oscillator with the output of the phase detector so that the output frequency of the second frequency variable oscillator is twice as high as the frequency of the reference signal on the communications satellite. The first frequency variable oscillator is replaced by a reference oscillator of constant frequency in a reference station.