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.

A wide-range VCO with optimum temperature adaptive tuning

Abstract: This paper presents an integrated wide-range VCO with a modified tuning scheme to deal with VCO frequency drift over temperature. In this approach, during the coarse-tune operation, VCO tune voltage is a function of temperature such that it resembles the inverse function of VCO fine-tune characteristic. Without degrading VCO performance, the proposed temperature adaptive tuning optimizes the maximum tolerable VCO temperature frequency drift over which PLL remains locked. As a result, VCO gain can be reduced significantly, making VCO less sensitive to PLL tune voltage noise. Integrated in a multi-standard multi-band transceiver with a small VCO gain of 50MHz/V at 3.90GHz, PLL remains locked despite 45MHz frequency drift of VCO over [−30°C, 85°C]. Using an on-chip inductor, VCO covers from 3.15GHz to 4.60GHz, achieving −138.0dBc/Hz phase noise at 3.0MHz at 3.90GHz by drawing just 8.5mA from 1.60V supply in 0.13u CMOS process.

Device and method for fast transition from preamble synchronization to data demodulation in direct sequence spread spectrum (DSSS) communications

Abstract: A device for fast transition from preamble synchronization of a received baseband signal to demodulation of the received baseband signal may include a baseband chip tracking loop to generate an offset tracking value to track any initial chip phase offset and Doppler-caused baseband chip frequency drift associated with the received baseband signal. The device may also include a numerical controlled oscillator to correct any Doppler-caused phase rotation associated with the received signal. The device may additionally include a preamble synchronization unit to detect a preamble of the received baseband signal, and to measure a chip phase offset and a baseband Doppler frequency shift associated with the received baseband signal. The chip phase offset may be used to set an initial chip phase offset value of the chip tracking loop so that the chip tracking loop starts with approximately a zero pull-in error. The baseband Doppler frequency shift may be used to set initial frequency offset values in the chip tracking loop and the numerical controlled oscillator so that both start with substantially near-zero offset errors for substantially immediate demodulation of the received signal. The device may further include an output device to output the data demodulated from the received baseband signal.

Voltage controlled oscillator, PLL circuit, pulse modulation signal generating circuit, semiconductor laser modulation device and image forming apparatus

Abstract: An oscillation frequency control part includes a voltage-to-current converting circuit converting an input voltage to a current having a value corresponding to the input voltage, and outputting a current in proportion to the current obtained from the voltage-to-current converting circuit An oscillating circuit part includes a ring oscillator, wherein a current in proportion to the output current of the oscillation frequency control part flows through the ring oscillator so that the oscillation frequency in the ring oscillator is controlled by the output current of the oscillation frequency control part The voltage-to-current converting circuit has linear voltage-to-current conversion characteristics in a predetermined range of the input voltage including a ground potential

Increasing the frequency stability of single‐frequency lasers

Abstract: We have developed an improved technique to increase the stability of single‐frequency lasers by employing a scanning Fabry–Perot interferometer and a stabilized helium neon laser. Our instrument surpasses earlier devices in several key areas. The laser frequency can now be stabilized while scanned across its inherent single‐frequency tuning range. The frequency stability is long term with an increased frequency correction rate of nearly 500 Hz. The laser frequency can be scanned repeatedly with a repetition accuracy equal to the frequency stability. Also, the electronics permit the laser frequency to be swept externally while synchronized with other instruments. Our stabilizer reduced the frequency drift of a commercial ring dye laser to ±1 MHz relative to the reference laser.

Low Frequency Coupled Oscillator and its Application to High Polymer Study

Abstract: For the study of dynamical properties of high polymers by low frequency oscillations, a simple torsional coupled oscillator was constructed in which two pendulums of the same type having equal frequency (about 1/2 c.p.s.) were coupled to each other through a test material of cylindrical shape. Two modes of oscillations appear in the motion of the oscillator resulting in generating beats under suitable conditions. By observing the beats, it is possible to obtain the shear modulus and the elastic loss of the material through a simple course of calculation. Polymethyl methacrylate was investigated from about -20°C to about 150°C and anomalous absorption ranges were found at about 130°C and at about 20°C, the latter was considered worthy of mention.