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682results about "Electrial characteristics varying frequency control" patented technology

Noise reduction within an electronic device using automatic frequency modulation

Disclosed is a system and method for providing an oscillating signal of relatively precise frequency without using a signal provided by a crystal as a reference. Disclosed is a feedback oscillator circuit configured to output an oscillating signal having a frequency defined by a reference signal. The oscillating signal can be sent to one or more circuits including at least one frequency sensitive element. The frequency sensitive element produces an output signal which depends on the frequency of the oscillating signal. A controller controls the reference signal in order to cause an attribute of the output signal to have a value within a desired range.
Owner:APPLE INC

Systems and methods for automated resonant circuit tuning

An apparatus and method for automatically tuning a resonant circuit in a chiroptical measurement system. A sample cell holds a sample being measured for a chiroptical property as the sample is modulated by the resonant circuit. A signal source coupled to the resonant circuit generates a driving signal at one of a plurality of frequencies to modulate the resonant circuit. The frequencies are within a range of expected resonant frequencies for the resonant circuit. A feedback loop circuit coupled to the signal source is used to adjust the frequency of the driving signal to another of the frequencies in response to a feedback signal associated with a measured parameter of the driving signal. In this way, the frequency of the driving signal is adjusted to create a resonant condition. The driving signal may also be applied at a reduced power level so that the resonant circuit can be driven at off-resonant frequencies within the range of frequencies.
Owner:GIBBS PHILLIP R

Miniature resonating marker assembly

A miniature resonating marker assembly that includes, in one embodiment, a ferromagnetic core, a wire coil disposed around the core, and a capacitor connected to the wire coil adjacent to the magnetic core. The core, coil, and capacitor form a signal element that, when energized, generates a magnetic field at a selected resonant frequency. The magnetic field has a magnetic center point positioned along at least one axis of the signal element. An inert encapsulation member encapsulates the signal element therein and defines a geometric shape of the resonating marker assembly. The geometric shape has a geometric center point substantially coincident with the magnetic center point along at least a first axis of the signal element. The shape and configuration of the assembly also provides for a miniature signal element specifically tuned to resonate at a selected frequency with a high quality factor.
Owner:VARIAN MEDICAL SYSTEMS

Temperature compensated oscillator including MEMS resonator for frequency control

Disclosed is an oscillator that relies on redundancy of similar resonators integrated on chip in order to fulfill the requirement of one single quartz resonator. The immediate benefit of that approach compared to quartz technology is the monolithic integration of the reference signal function, implying smaller devices as well as cost and power savings.
Owner:RGT UNIV OF CALIFORNIA

Radio frequency control for communication systems

The present invention provides for a system and method for improvement of radio transmitter and receiver frequency accuracy for a local radio communication unit that communicates digital data with a remote communication unit. In the local unit the received radio signal is down-converted, and converted to complex baseband digital samples by an analog-to-digital converter. A downlink digital phase rotator applies a fine frequency shift to the samples in accordance with a receiver frequency offset command. The resultant baseband signal is used by the data demodulator and by a receiver frequency error estimator to obtain receiver frequency errors. A data modulator generates baseband complex samples which are shifted in carrier frequency by an integrated uplink digital phase rotator in accordance with a transmitter frequency offset command. The modulated samples are then converted by a digital-to-analog converter and upconverted in frequency for radio transmission to the remote unit. The local oscillator signals for both upconverter and downconverter are phase locked to a reference frequency generated by a VCXO. An automatic frequency control (AFC) function nulls the transmitter and receiver frequency error by the frequency adjustment commands to the uplink and downlink phase rotators or to the VCXO digital-to-analog converter (VCXO DAC) by feedback control principals based on measured receiver frequency error. During frequency track mode when communications between local and remote units are possible, the AFC only adjusts radio frequency via phase rotator commands and the VCXO command remains fixed, thereby avoiding communications performance degradation by VCXO frequency quantization error due to the VCXO DAC. The AFC adjusts VCXO frequency only during a preliminary acquisition mode prior to data communications, or to back out excessively large frequency offsets accumulated in the downlink and uplink phase rotators during track mode. When a VCXO adjustment is made in track mode, phase rotator adjustments are simultaneously applied to cancel the errors in transmitter and receiver radio frequencies caused by the step change due to VCXO frequency quantization thereby mitigating VCXO frequency quantization noise.
Owner:AVAGO TECH WIRELESS IP SINGAPORE PTE

System and method for frequency offsetting of information communicated in mimo-based wireless networks

A communications system includes a multiple-input / multiple-output (MIMO) architecture for high capacity switched mesh networks. The MIMO architecture has a plurality of radio frequency chains. One of the plurality of radio frequency chains is configured to apply a first frequency offset to a base frequency of an output signal to generate a first transmitting frequency; and another of the plurality of radio frequency chains being configured to apply a second frequency offset to the base frequency to generate a second transmitting frequency. The system uses the carrier frequency offset to lock the clock of the master subsystem to the clock of the slave subsystem, thereby enabling bandwidth expansion to be employed on the MIMO data streams.
Owner:TELEFON AB LM ERICSSON (PUBL)

Radio frequency control for communication systems

The present invention provides for a system and method for improvement of radio transmitter and receiver frequency accuracy for a local radio communication unit that communicates digital data with a remote communication unit. In the local unit the received radio signal is down-converted, and converted to complex baseband digital samples by an analog-to-digital converter. A downlink digital phase rotator applies a fine frequency shift to the samples in accordance with a receiver frequency offset command. The resultant baseband signal is used by the data demodulator and by a receiver frequency error estimator to obtain receiver frequency errors. A data modulator generates baseband complex samples which are shifted in carrier frequency by an integrated uplink digital phase rotator in accordance with a transmitter frequency offset command. The modulated samples are then converted by a digital-to-analog converter and upconverted in frequency for radio transmission to the remote unit. The local oscillator signals for both upconverter and downconverter are phase locked to a reference frequency generated by a VCXO. An automatic frequency control (AFC) function nulls the transmitter and receiver frequency error by the frequency adjustment commands to the uplink and downlink phase rotators or to the VCXO digital-to-analog converter (VCXO DAC) by feedback control principals based on measured receiver frequency error. During frequency track mode when communications between local and remote units are possible, the AFC only adjusts radio frequency via phase rotator commands and the VCXO command remains fixed, thereby avoiding communications performance degradation by VCXO frequency quantization error due to the VCXO DAC. The AFC adjusts VCXO frequency only during a preliminary acquisition mode prior to data communications, or to back out excessively large frequency offsets accumulated in the downlink and uplink phase rotators during track mode. When a VCXO adjustment is made in track mode, phase rotator adjustments are simultaneously applied to cancel the errors in transmitter and receiver radio frequencies caused by the step change due to VCXO frequency quantization thereby mitigating VCXO frequency quantization noise.
Owner:AVAGO TECH WIRELESS IP SINGAPORE PTE

Method and apparatus for fully integrating a voltage controlled oscillator on an integrated circuit

A method and apparatus for fully integrating a Voltage Controlled Oscillator (VCO) on an integrated circuit. The VCO is implemented using a differential-mode circuit design. The differential-mode implementation of the VCO preferably comprises a differential mode LC-resonator circuit, a digital capacitor, a differential pair amplifier, and a current source. The LC-resonator circuit includes at least one tuning varactor and two high Q inductors. The tuning varactor preferably has a wide tuning capacitance range. The tuning varactor is only used to "fine-tune" the center output frequency f0 of the VCO. The center output frequency f0 is coarsely tuned by the digital capacitor. The VCO high Q inductors comprise high gain, high self-resonance, and low loss IC inductors. The IC VCO is fabricated on a high resistivity substrate material using a trench isolated guard ring. The guard ring isolates the fully integrated VCO, and each of its component parts, from RF signals that may be introduced into the IC substrate by other devices. By virtue of the improved performance characteristics provided by the digital capacitor, the analog tuning varactor, the high Q inductor, and the trench isolated guard ring techniques, the inventive VCO is fully integrated despite process variations in IC fabrication.
Owner:CSR TECH INC

Systems and methods for providing an adjustable reference signal to RF circuitry

Frequency modification circuitry may be employed as part of a crystal oscillator circuit to generate a reference signal with adjustable frequency. The frequency modification circuitry may be implemented as part of a crystal oscillator circuit that includes digitally controlled crystal oscillator (“DCXO”) circuitry and a crystal. The frequency modification circuitry may adjust the frequency of the reference signal in response to one or more frequency control signals. In one example, the frequency modification circuitry may include variable capacitors such as one or more continuously variable and / or discretely variable capacitors for providing coarse and / or fine adjustment of the reference signal frequency.
Owner:SILICON LAB INC

MEMS-based, computer systems, clock generation and oscillator circuits and LC-tank apparatus for use therein

MEMS-based, computer system, clock generation and oscillator circuits and LC-tank apparatus for use therein are provided and which are fabricated using a CMOS-compatible process. A micromachined inductor (L) and a pair of varactors (C) are developed in metal layers on a silicon substrate to realize the high quality factor LC-tank apparatus. This micromachined LC-tank apparatus is incorporated with CMOS transistor circuitry in order to realize a digital, tunable, low phase jitter, and low power clock, or time base, for synchronous integrated circuits. The synthesized clock signal can be divided down with digital circuitry from several GHz to tens of MHz—a systemic approach that substantially improves stability as compared to the state of the art. Advanced circuit design techniques have been utilized to minimize power consumption and mitigate transistor flicker noise upconversion, thus enhancing clock stability.
Owner:RGT UNIV OF MICHIGAN

Method and apparatus for compensating local oscillator frequency error

The frequency error of an oscillator is minimized by characterizing the oscillator. A reference signal from an external source containing a minimal frequency error is provided to an electronic device. The external signal is used as a reference frequency to estimate the frequency error of an internal frequency source. The electronic device monitors parameters that are determined to have an effect on the frequency accuracy of the internal frequency source. Temperature is one parameter known to have an effect on the frequency of the internal frequency source. The electronic device collects and stores the values of the parameters as well as the corresponding output frequency or frequency error of the internal frequency source. The resultant characterization of the internal frequency source is used to compensate the internal frequency source when the internal frequency source is not provided the external reference signal.
Owner:QUALCOMM INC

Integrated Tuner for Terrestrial and Cable Television

A highly integrated terrestrial and cable tuner for receiving digital and analog television signals is disclosed. It achieves high performances in sensitivity, image rejection, dynamic range, channel selectivity and power consumption. A major-images rejection converter disclosed rejects third- and fifth-order images. Thus it significantly relaxes RF filter design in a tuner of a single-stage or a first-stage zero-IF / low-IF downconversion architecture. Different architectures and frequency planning are disclosed in accordance with specifications of TV standards to improve the overall performance of the tuner with a different or configurable IF output. The tuner is integrated by using standard processes, with minimal off-chip components excluding SAW and LC filters. Small tuner modules cost less than discrete (can) tuners. They can be used in digital / analog TV sets and portable and handheld TV devices and for mobile-phone TV reception.
Owner:PAN JIANPING

Multi-mode communications system with efficient oscillator synchronization

A system for synchronizing a second receive chain relative to a first receive chain in a multi-mode communication system. The system includes a first circuit that measures a first frequency associated with the first receive chain. A second circuit adjusts a second frequency associated with the second receive chain based on the first frequency and provides a desired second frequency to the second receive chain in response thereto. In a specific embodiment, the first circuit includes a first counter that receives a signal associated with an output of a first oscillator and provides a measurement of the first frequency in response thereto. The second circuit includes a frequency synthesizer for providing the desired second frequency in response to a frequency control or reference signal. Another circuit generates the control or reference signal based on a difference between the second frequency and the first frequency. A second counter receives a signal characterized by the second frequency and provides the second frequency in response thereto.
Owner:QUALCOMM INC

Digital cordless communication system with frequency deviation correction capability

A digital cordless telecommunication system capable of maintaining the enhanced frequency stability of radio transmission signals from stationary base stations by use of a specific clock signal including either a high-precision clock or a reference clock as generated by main equipment. In this system the main equipment is provided with a high-precision oscillator that generates and issues a clock signal with increased pulse-phase accuracy, whist a respective one of the base stations is with a line interface for extraction of such high-precision clock signal from the high-precision oscillator, a reference oscillator which supplies a reference clock to a frequency synthesizer that generates a local oscillation signal, a frequency error detector operable to detect a difference or "error" in frequency between the reference clock of the reference oscillator and the high-precision clock of the line interface, and a reference oscillator controller which is responsive to receipt of the error signal from the frequency error detector for adjusting any possible frequency deviation of the reference oscillator causing the reference clock frequency of the reference oscillator to keep track of the frequency of the high-precision clock signal.
Owner:PANASONIC CORP

Ring oscillator having variable coarse and fine delays

A ring oscillator includes a coarse delay control block including a plurality of coarse delay gates, and a fine delay control block including a plurality of fine delay gates. The total delay of the fine delay control block is larger than a single delay step of the coarse delay control block, whereby variations of the delay step do not cause an adverse effect on the jitter characteristic of a PLL circuit having the ring oscillator. In a normal operation, the coarse delay control block increments the delay step after the total of the delay steps of the fine delay control block exceeds the delay step of the coarse delay control block.
Owner:RENESAS ELECTRONICS CORP

Ring oscillator using current mirror inverter stages

A ring oscillator having an odd number of single ended stages, each stage including two transistors connected as a current mirror. The stage provides for low-voltage performance and improved process tolerance characteristics.
Owner:STMICROELECTRONICS SRL

LC oscillator with wide tuning range and low phase noise

A voltage-controlled oscillator including an active oscillator circuit, an inductor, and capacitive circuits is disclosed. The capacitive circuits are selectively turned on and off to control the frequency of the voltage-controlled oscillator. Particularly, the inductor and the capacitors in the capacitive circuits form LC circuits that provide feedback to the active oscillator circuit. To avoid damage to the switches in the capacitive circuits, the capacitive circuits further comprise resistors. The resistors can be configured in several different ways so that the voltage-controlled oscillator can have a high degree of reliability, and a wide tuning range with constant phase noise performance.
Owner:GCT SEMICONDUCTOR INC

On-chip VCO calibration

Embodiments of the invention provide techniques for calibrating voltage-controlled oscillators (VCOs). Multiple VCOs may be disposed on a chip with the VCOs having different frequency ranges. The VCOs may be selected and tested to determine a desired VCO to use to tune to a selected channel frequency. Each of the VCOs has multiple possible varactor configurations. The varactor configurations of the desired VCO determined to be used to tune to the selected channel frequency can be selected and tested to determine a desired varactor configuration for the desired VCO. The desired VCO with the desired varactor configuration will preferably be able to produce a full range of desired frequencies corresponding to all channel frequencies desired.
Owner:SKYWORKS SOLUTIONS INC

Spectrum spread clock generation device

A spread spectrum controller (20) controls a PLL (10) so that the PLL outputs a spread-spectrum processed clock signal. A loop bandwidth controller (30) controls at least one of a phase detector (11), a loop filter (12), a voltage-controlled oscillator (13), and a frequency divider (14) in the PLL (10) during operation of the spread spectrum controller (20) to change a loop bandwidth of the PLL (10).
Owner:PANASONIC CORP

Wireless communication unit, integrated circuit and method for antenna tuning

A wireless communication unit includes an antenna arrangement; an aperture tuner operably coupled to a first port of the antenna arrangement; a measurement circuit operably coupled to an antenna input feed point of the antenna arrangement and arranged to measure a parameter. A controller, operably coupled to the aperture tuner, is arranged to perform closed loop aperture tuning using the measured parameter.
Owner:MEDIATEK SINGAPORE PTE LTD SINGAPORE

Partitioning of radio-frequency apparatus

Components of a radio-frequency (RF) apparatus including transceiver circuitry and frequency modification circuitry of a crystal oscillator circuit that generates a reference signal with adjustable frequency may be partitioned in a variety of ways, for example, as one or more separate integrated circuits. The frequency modification circuitry may be implemented as part of a crystal oscillator circuit that includes digitally controlled crystal oscillator (“DCXO”) circuitry and a crystal. The frequency modification circuitry may include at least one variable capacitance device and may be employed to generate a reference signal with adjustable frequency. The adjustable reference signal may be provided to other components of the RF apparatus and / or the RF apparatus may be configured to provide the adjustable reference signal to baseband processor circuitry. Automatic frequency control (AFC) circuitry may be integrated with other components of RF circuitry and may generate frequency control signals for the frequency modification circuitry based on, for example, a signal received from a temperature sensor. Digital-to-analog converter (DAC) circuitry may be integrated with other components of RF circuitry to enable all-digital frequency control communications from baseband processor circuitry to RF circuitry.
Owner:SILICON LAB INC
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