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Showing papers on "Frequency drift published in 2004"


Patent
Yue Wu1
05 Feb 2004
TL;DR: In this paper, a VCO with temperature compensation is achieved using reverse biased diodes, which can be controlled by a reverse bias voltage to compensate for drift in the VCO oscillation frequency over temperature.
Abstract: A VCO with temperature compensation is achieved using reverse biased diodes. The VCO includes an amplifier that provides the required signal gain, a resonator tank circuit that provides the required phase shift, and at least one frequency tuning circuit for tuning the frequency of the oscillator signal. Each frequency tuning circuit includes at least one tuning capacitor and at least one MOS pass transistor that connects or disconnects the tuning capacitor(s) to/from the resonator tank circuit. Each reverse biased diode may be a parasitic diode that is formed at a drain or source junction of a MOS transistor. The reverse biased diodes have capacitance that can be controlled by a reverse bias voltage to compensate for drift in the VCO oscillation frequency over temperature.

71 citations


Journal ArticleDOI
TL;DR: In this article, the high frequency properties of a carbon-nanotube-based three-terminal nanoelectromechanical relay were theoretically investigated, and the intrinsic mechanical frequency of the relay is in the GHz regime, and electromechanical coupling shows a non-linear resonant behaviour in this frequency range.
Abstract: We have theoretically investigated the high frequency properties of a carbon-nanotube-based three-terminal nanoelectromechanical relay. The intrinsic mechanical frequency of the relay is in the GHz regime, and the electromechanical coupling shows a non-linear resonant behaviour in this frequency range. We discuss how these resonances may be detected and show that the resonance frequencies can be tuned by the bias voltage. Also, we show that the influence of external electromagnetic fields on the relay is negligible at all frequencies.

63 citations


Journal ArticleDOI
TL;DR: A novel receiver which combines the current ICI self-cancellation coding techniques with a new expectation-maximization-based joint phase/amplitude estimation and symbol detection scheme is proposed and compared with other existing methods at different noise levels through OFDM simulations.
Abstract: OFDM has been applied in the current wireless local-area networks and digital video broadcasting systems since it has the advantage over the conventional single-carrier modulation schemes when the frequency-selective fadings are present. Nevertheless, intercarrier-interference (ICI) due to Doppler frequency drift, phase offset, local oscillator frequency drift, and multipath fading will be a severe problem in OFDM systems. Previous ICI self-cancellation coding schemes can greatly reduce the ICI, but they are very sensitive to the phase ambiguity, which is due to the composite effect of the phase offset, the multipath fading and the local frequency drift. In this paper, the phase ambiguity and amplitude ambiguity problems in ICI self-cancellation coded OFDM receivers will be formulated and discussed. Then, a novel receiver which combines the current ICI self-cancellation coding techniques with a new expectation-maximization-based joint phase/amplitude estimation and symbol detection scheme is proposed. The outstanding performance of this proposed scheme is shown and compared with other existing methods at different noise levels through OFDM simulations.

61 citations


Journal ArticleDOI
TL;DR: The measurement of an Erbium-fiber oscillator's carrier-envelope-offset frequency using an extruded SF6 photonic crystal fiber for the generation of a more than two octave-spanning supercontinuum from 400 nm to beyond 1750 nm is reported.
Abstract: We report on the measurement of an Erbium-fiber oscillator’s carrier-envelope-offset frequency using an extruded SF6 photonic crystal fiber for the generation of a more than two octave-spanning supercontinuum from 400 nm to beyond 1750 nm. A modified type of f-2f-interferometer was employed, beating the frequency doubled input signal of the fiber oscillator with the supercontinuum to generate the carrier-envelope-offset beat. Controlling the fiber oscillator’s pump power with an electronic feedback loop, we phase-locked the carrier-envelope-offset frequency to an external reference source. The resulting residual phase excursions correspond to fractional frequency instabilities of the oscillator’s frequency comb of the order of 10-16 for averaging times longer than 10 s.

52 citations


Patent
01 Dec 2004
TL;DR: In this article, a power supply controller has a variable frequency oscillator that is used for controlling a PWM controller, and the controller varies the frequency of the oscillator to control the PWM.
Abstract: In one embodiment, a power supply controller has a variable frequency oscillator that is used for controlling a PWM controller. The power supply controller varies a frequency of the variable frequency oscillator.

48 citations


Patent
10 Jun 2004
TL;DR: In this paper, a method for calibrating an on-chip non-precision oscillator is presented, where the oscillator's period is measured as a function of the time base.
Abstract: Method and apparatus for calibration of a low frequency oscillator in a processor based system. A method for calibrating an on-chip non-precision oscillator. An on-chip precision oscillator is provided having a known frequency of operation that is within an acceptable operating tolerance. The on-chip precision oscillator is used as a time base and then the period of the on-chip oscillator is measured as a function of the time base. The difference between the measured frequency of the on-chip non-precision oscillator and a desired operating frequency of the on-chip non-precision oscillator is then determined. After the difference is determined, the frequency of the on-chip non-precision oscillator is adjusted to minimize the determined difference.

47 citations


Journal ArticleDOI
TL;DR: In this article, the authors used a Fabry-Pe/spl acute/rot etalon to stabilize the laser frequency against long-term drifts, achieving a frequency accuracy of /spl plusmn/3 GHz.
Abstract: We demonstrate wavelength locking in a widely tunable fast-switching laser module that accesses 64 ITU channels with 50-GHz spacing and switches wavelength in under 50 ns. We use a Fabry-Pe/spl acute/rot etalon to stabilize the laser frequency against long-term drifts. We demonstrate locking while continuously switching with random channel schedules of 1-/spl mu/s packets. The locked frequency accuracy of /spl plusmn/3 GHz is a factor of two improvement over operation without locking. We also present the dynamics of the frequency drift due to temperature variation in the laser, and show the correlation between the frequency offsets while locking and the electrical power dissipated in the tuning sections.

44 citations


Patent
27 Oct 2004
TL;DR: In this article, a cycle time detector is used to determine the quantity of delay elements within a clock cycle and adjust a DLL counter controlling a variable delay line to enable operation or locking in response to DLL overflow and underflow conditions.
Abstract: A delay locked loop (DLL) according to the present invention includes a cycle time detector to determine the quantity of delay elements within a clock cycle and adjust a DLL counter controlling a DLL variable delay line to enable operation or locking in response to DLL overflow and underflow conditions. The cycle time detector includes a ring oscillator having a strong correlation between the oscillator period and the DLL delay elements. The output of the oscillator controls the counter to provide a new locking position for the DLL in the presence of overflow or underflow conditions. The oscillator is driven for an interval corresponding to the product of the external clock period and the quantity of delay elements in the ring oscillator. In effect, the delay of the DLL is adjusted to the preceding or succeeding external clock period to enable locking in response to overflow or underflow conditions.

42 citations


Proceedings ArticleDOI
23 May 2004
TL;DR: The design of a temperature compensated IC on-chip oscillator and a low voltage detection circuitry sharing the bandgap reference is described, which includes a new bandgap isolation strategy to reduce oscillator noise coupled through the current sources.
Abstract: The design of a temperature compensated IC on-chip oscillator and a low voltage detection circuitry sharing the bandgap reference is described. The circuit includes a new bandgap isolation strategy to reduce oscillator noise coupled through the current sources. The IC oscillator provides a selectable clock (11.6 MHz or 21.4 MHz) with digital trimming to minimize process variations. After fine-tuning the oscillator to the target frequency, the temperature compensated voltage and current references guarantees less than /spl plusmn/2.5% frequency variation from -40 to 125/spl deg/C, when operating from 3 V to 5 V of power supply. The low voltage detection circuit monitors the supply voltage applied to the system and generates the appropriate warning or even initiates a system shutdown before the in-circuit SoC presents malfunction. The module was implemented in a 0.5 /spl mu/m CMOS technology, occupies an area of 360 /spl times/ 530 /spl mu/m/sub 2/ and requires no external reference or components.

39 citations


Patent
Han-il Lee1, In-Chul Hwang1
15 Sep 2004
TL;DR: In this article, a frequency synthesizer with an adaptive frequency calibration circuit and a phase-locked loop (PLL) is presented. But the PLL does not control the output phase of the voltage-controlled oscillator.
Abstract: A frequency synthesizer is provided. The frequency synthesizer includes an adaptive frequency calibration circuit and a phase locked loop (PLL). The frequency synthesizer performs in a frequency lock mode and in a phase lock mode. In the frequency lock mode, the adaptive frequency calibration circuit compares the frequency of an input signal with the frequency of an output signal of a voltage controlled oscillator of the PLL and outputs control bits as a result of the comparison. The voltage controlled oscillator has a plurality of operating characteristic curves and selects a curve from among the plurality of operating characteristic curves in response to the control bits. In the phase lock mode, the PLL controls an output phase of the voltage controlled oscillator based on a tuning voltage from the selected operating characteristic curve.

38 citations


Journal ArticleDOI
TL;DR: In this paper, the results of radio telescope UTR-2 observations of solar Type II radio bursts in the 10-30-MHz frequency range are presented, which possess a fine structure consisting of fast drift sub-bursts similar to Type II bursts.
Abstract: We present the results of radio telescope UTR-2 observations of solar Type II radio bursts in the 10–30 MHz frequency range. These events possess a fine structure consisting of fast drift sub-bursts similar to Type III bursts. The frequency drift rate of the Type II bursts at decameter wavelengths is smaller than 0.1 MHz s−1. One of these bursts with herringbone structure has a wave-like backbone that almost does not drift. The features of the observed bursts are discussed.

Patent
19 Aug 2004
TL;DR: In this article, a Kalman filter was used as an adaptive filter to predict the future frequency state of the oscillator on which it was trained, using the predicted frequency of the model as a reference to correct the frequency of an oscillator in the event that no input reference timing signal is available.
Abstract: A reference timing signal apparatus with a phase-locked loop has a computer algorithm which adaptively models the multiple frequencies of an oscillator following a training period. The oscillation frequency of the oscillator is controlled in response to a phase detector output. The computer algorithm processes the control signal applied to the oscillator. The computer algorithm updates the characteristics of the model relating to the aging and temperature of the oscillator, using for example, a Kalman filter as an adaptive filter. By the algorithm, the subsequent model predicts the future frequency state of the oscillator on which it was trained. The predicted frequency of the model functions as a reference to correct the frequency of the oscillator in the event that no input reference timing signal is available. In a case of using pre-processing infinite impulse response filters (IIRFs) before the adaptive processor, the time delay caused by the filters are compensated after the adaptive processor. Without pre-processing IIRFs, aging and temperature update rates are adaptively controlled by dynamically changing the rates depending upon the loop condition to achieve a wider tracking bandwidth. With the model updating algorithm, oscillators of low stability performance may be used as cellular base station reference oscillator.

Journal ArticleDOI
TL;DR: In this paper, a dispersion relation for ultralow frequency drift compressional modes in high pressure plasmas with finite gyroradius is derived from the linearized gyrokinetic-Maxwell equations with cold electrons and narrow eigenmode localization width along the field line.
Abstract: [1] A dispersion relation for ultralow frequency drift compressional modes in high pressure plasmas with finite gyroradius is derived from the linearized gyrokinetic-Maxwell equations with cold electrons and narrow eigenmode localization width along the field line. The dispersion relation demonstrates instability under two different conditions: 1) when the density gradient and proton temperature gradient are in opposite directions, or 2) when the magnetic guiding center drift is reversed with respect to the proton diamagnetic drift, i.e., drift reversal, which could occur during periods of strong magnetospheric disturbance. Furthermore, it is found that the most unstable modes have short azimuthal wavelengths comparable to the proton gyroradius.

Patent
23 Dec 2004
TL;DR: In this paper, a low-IF mixer and method for down-converting a signal at a desired frequency are disclosed with improved selectivity performance, where the energy of sidebands on each side of the desired frequency is evaluated; and a local oscillator frequency is selected based on the evaluation of the energy.
Abstract: A low IF mixer and method for down-converting a signal at a desired frequency are disclosed with improved selectivity performance. The energy of sidebands on each side of the desired frequency is evaluated; and a local oscillator frequency is selected based on the evaluation of the energy. Generally, the local oscillator frequency associated with the sideband having a lower energy is selected. The desired frequency may have a frequency of RF and the sidebands have a frequency of the desired frequency plus or minus an offset frequency (RF+IF or RF−IF). The signal at the desired frequency may be multiplied by the selected local oscillator frequency to down-convert the signal.

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.

Patent
17 Jun 2004
TL;DR: In this article, a digital adaptive gain control loop is used to directly modulate the VCO, and a phase-locked loop (PLL) is applied to track the carrier frequency without passing the modulation signal into the PLL loop filter.
Abstract: Techniques for direct modulation of a voltage-controlled oscillator (VCO) with adaptive digital gain control for wideband wireless applications are disclosed. A digital adaptive gain control loop is used to directly modulate the VCO, and a phase-locked loop (PLL) to track the frequency drift and other nonlinear effects of the VCO. As the PLL is applied to track the carrier frequency without passing the modulation signal into the PLL loop filter, the PLL can be implemented with a narrow loop bandwidth. The wideband frequency modulated signal is directly up-converted to the radio frequency (RF) signal by directly modulating the VCO through a digital-to-analog converter which is digitally controlled by an adaptive gain control loop. Thus, both wide bandwidth and low output noise for a frequency synthesizer and modulator can be achieved.

Patent
24 Nov 2004
TL;DR: In this paper, a frequency phase correction system and method are described that provides a receiver with a greater ability to lock onto relatively weak radio frequency signals by determining and estimating an amount of frequency error in a local frequency reference of the receiver, and using the error estimate to maintain frequency coherence with a received signal.
Abstract: A frequency phase correction system and method are described that provides a receiver with a greater ability to lock onto relatively weak radio frequency signals by determining and estimating an amount of frequency error in a local frequency reference of the receiver, and using the error estimate to maintain frequency coherence with a received signal, thereby allowing tracking over a longer period of time, enabling longer integration times to capture weaker signals without losing frequency coherence.

Patent
21 Jul 2004
TL;DR: In this paper, a voltage controlled crystal oscillator (VCXO) is proposed for generating a desired reference frequency in a wireless terminal with a reduced start-up time, without negatively impacting the DC current consumption or the tuning range of the VCXO.
Abstract: A voltage controlled oscillator, such as a VCXO (Voltage Controlled Crystal Oscillator), for generating a desired reference frequency in a wireless terminal with a reduced start-up time is described herein. According to the present invention, the VCXO comprises an oscillator that generates the desired reference frequency based on a variable voltage applied to the oscillator by a voltage controller. In addition, the VCXO includes a start-up controller that applies a bias voltage to an oscillator input node to reduce a capacitance associated with the oscillator, and therefore, to reduce the start-up time without negatively impacting the DC current consumption or the tuning range of the VCXO.

Patent
27 May 2004
TL;DR: 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 as mentioned in this paper.
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

Patent
15 Oct 2004
TL;DR: In this paper, methods and systems of adjusting an oscillator frequency are disclosed. One example method includes reading a temperature associated with an oscillators, reading a first tuning code associated with the temperature from a memory, and tuning the oscillator with the first tune code.
Abstract: Methods and systems of adjusting an oscillator frequency are disclosed. One example method includes reading a temperature associated with an oscillator, reading a first tuning code associated with the temperature from a memory, and tuning the oscillator with the first tuning code. The example method may further include determining a second tuning code, and storing the second tuning code and an indication of the temperature in the memory.

Patent
06 Feb 2004
TL;DR: In this paper, a sweep mode function was proposed to provide frequency compensation over a range of frequency drift broader than the frequency drift accommodated by a phase lock loop, without increasing the noise characteristics of the phase lock loops.
Abstract: Systems and methods for providing frequency compensation over a wide range of frequency drift are shown. The preferred embodiment utilizes a sweep mode function to provide frequency compensation over a range of frequency drift broader than the frequency drift accommodated by a phase lock loop, without increasing the noise characteristics of the phase lock loop. Accordingly, the preferred embodiment operates in a phase lock loop mode while frequency drift can be compensated for by the lock range of the phase lock loop circuitry. The preferred embodiment operates in sweep mode to step through a range of offset frequencies to position the phase lock loop mode where frequency drift can be compensated for by the lock range of phase lock loop circuitry. Additionally, a preferred embodiment of the present invention includes a drift mode in order to monitor frequency offset information, such as may be used in performing sweep mode functions and/or other control or management functions.

Patent
30 Jan 2004
TL;DR: In this paper, a self-calibrating radio is described, which automatically calibrates the radio by receiving a reference signal having a calibrated reference frequency, and comparing the local frequency to the reference frequency to determine whether there is a difference between the local frequencies and the reference frequencies.
Abstract: A self-calibrating radio is described. In one exemplary implementation, a radio generates a radio signal from its local voltage controlled oscillator. The calibration system automatically calibrates the radio by: (i) receiving a reference signal having a calibrated reference frequency, (ii) comparing the local frequency to the reference frequency to determine whether there is a difference between the local frequency and the reference frequency and (iii) adjusting the local frequency by an offset frequency, if the difference between the local frequency and the reference frequency is greater than a threshold value.

Proceedings ArticleDOI
06 Dec 2004
TL;DR: In this article, a two-stage CMOS voltage controlled ring oscillator with wide operating frequency tuning range is presented with a 1.8/spl mu/m CMOS technology and biased at 18V supply voltage.
Abstract: A 900-MHz two-stage CMOS voltage controlled ring oscillator with wide operating frequency tuning range is presented in This work It is implemented with a 018-/spl mu/m CMOS technology and biased at 18-V supply voltage Its frequency tuning range is from 440 MHz to 1595 MHz The VCO can function even biased at 1 V And the phase noise is -733 dBc/Hz at 100 kHz frequency offset and -93 dBc/Hz at 1MHz

Journal ArticleDOI
TL;DR: In this paper, a wavelet analysis shows the frequency drift from 1 kHz ( below the low hybrid frequency) to 200 Hz (below the proton cyclotron frequency) and the phase velocity of the wave packets is inversely proportional to the frequency.
Abstract: Several examples of whistler wave packets accompanied by density cavities are detected in F4 experiments of Freja satellite. The density depletion seems to be a fixed structure in space from the cross-correlation of two Langmuir probes. The wavelet analysis shows the frequency drift from 1 kHz ( below the low-hybrid frequency) to 200 Hz ( below the proton cyclotron frequency). The wave packets are always associated with an extremely low frequency component at 20-30 Hz ( around the oxygen ion cyclotron frequency). The method of the minimum variance is used to calculate the oblique propagation of the wave packets with an angle decreased from 31 to 17 degrees between the wave vector and the ambient magnetic field. The right polarization of the wave packets is shown in the direction of the ambient magnetic field. Moreover, the phase velocity of the wave packets is inversely proportional to the frequency. These features may support the formation of envelope solitary whistler waves.

Patent
22 Jun 2004
TL;DR: In this paper, a voltage controlled digital analog oscillator and a frequency synthesizer using the same, the oscillator comprising an oscillator having a frequency of an output signal being determined by a voltage inputted to an analog input end and a digital value inputting to a digital input end, is used to obtain a broadband frequency output with less noise.
Abstract: Provided are a voltage controlled digital analog oscillator and a frequency synthesizer using the same, the oscillator comprising an oscillator having a frequency of an output signal being determined by a voltage inputted to an analog input end and a digital value inputted to a digital input end; and a digital tuner for comparing the voltage inputted to the analog input end to first and second threshold voltages and changing the digital value inputted to the digital input end according to the result, whereby it is possible to obtain a broadband frequency output with less noise.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a frequency stability measuring technique that uses a two-channel audio band digitizer in place of the time interval counter, and obtained an Allan deviation (square root of the Allan variance) of σy(τ) = 5 × 10−17 at τ = 1000 seconds.
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

Patent
10 Dec 2004
TL;DR: In this paper, a method and an arrangement for interference compensation in a phase-locked loop comprising a voltage-controlled frequency generator, wherein the frequency generator is tuned to a nominal frequency by a tuning voltage Vtune and whose actual frequency is compared with a reference frequency by means of a frequency comparison and is re-adjusted if a deviation is detected via the frequency comparison.
Abstract: The invention, which relates to a method and an arrangement for interference compensation in a phase-locked loop comprising a voltage-controlled frequency generator, wherein the frequency generator is tuned to a nominal frequency by a tuning voltage Vtune and whose actual frequency is compared with a reference frequency by means of a frequency comparison and is re-adjusted if a deviation is detected via the frequency comparison, in which case, in the event of interference, the tuning voltage Vtune is changed by an interference voltage Vstor that depends on the interference event, and thus a frequency deviating from the nominal frequency is generated, which deviating frequency is corrected again by the phase locked loop, is based on the object to provide a method and an arrangement for interference compensation in a phase-locked loop comprising a voltage-controlled frequency generator, with which a deviation from a predefined nominal frequency is avoided if known interference events occur. The object is achieved in accordance with the invention in a method whereby, if a known interference event occurs, a voltage Vstor which compensates for the interference voltage Vcomp, is generated in synchronism with this with sign inversion and is superimposed on the interference voltage Vstor.

Patent
12 Mar 2004
TL;DR: In this paper, the interference in a frequency channel is determined by detecting multiple erroneous transmissions in the frequency channel, and the frequency channels with interference is then eliminated from the frequency hopping sequence.
Abstract: Frequency channel selection in a data transmission method uses a frequency hopping method. In a first method step, interference in a frequency channel is determined by detecting multiple erroneous transmissions in the frequency channel, and the frequency channel with interference is then eliminated from the frequency hopping sequence. In a second method step, the strength of external signals is measured within the frequency range of an eliminated frequency channel with interference, and the frequency channel is reinserted into the frequency hopping sequence if the strength is below a prescribed threshold value.

Patent
24 Jun 2004
TL;DR: In this article, an oscillation frequency changing means is inserted between a tuner and an oscillator of local oscillator (56) of a high frequency receiving device, and the OF changing means, in each frequency band received, changes the oscillation frequencies characteristic of LOS in relation to the tuning voltage supplied from PLL circuit (78).
Abstract: An oscillation frequency changing means is inserted between a tuner and an oscillator of local oscillator (56) of a high frequency receiving device, and the oscillation frequency changing means, in each frequency band received, changes the oscillation frequency characteristic of local oscillator (56) in relation to the tuning voltage supplied from PLL circuit (78), and operates in accordance with the frequency characteristic of tuning filter (52, 54, 62, 64) to obtain an oscillation signal varied just by a predetermined frequency, thereby making it possible to receive broadband channels of continuous VHF broadcast band and UHF broadcast band.

Patent
30 Aug 2004
TL;DR: In this article, an adaptive radio receiver in electronic communication devices (e.g., mobile phones) is designed by providing an automatic digital tuning of a voltage controlled oscillator of a phase locked loop (PLL) instead of a prior-art pre-calibration.
Abstract: This invention describes a method for a component/system level design of an adaptive radio receiver in electronic communication devices (e.g., mobile phones) by providing an automatic digital tuning of a voltage controlled oscillator of a phase locked loop (PLL) instead of a prior-art pre-calibration. A normal PLL for frequency locking is used which does not need any additional pre-calibration blocks to account for different temperatures or any other extreme conditions. If the current switch setting does not allow the locking, i.e., the VCO output signal frequency is still far away from a reference frequency, the PLL “coarse” tuning will cause the switch condition to change and bring the frequency within a reasonable range using an additional phase detector PD 2 loop.