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317results about "Resonant circuit tuning" patented technology

Method and apparatus for antenna tuning

A method for tuning a transmitter in order to improve impedance matching to an antenna or to intermediate radio frequency stages uses an error detector that senses a deviation of the amplitude or phase angle of a load current of a power amplifier driver or of a power amplifier. A controller calculates a correction and dynamically adjusts tunable transmitter parameters, which may include values of components in matching networks or bias voltages in the power amplifier or the power amplifier driver, so as to reduce the deviation and thereby improve the impedance matching. The load current of the power amplifier may alternatively be sensed by measuring the duty cycle of its switching mode power supply. A transmitter having a power amplifier and one or more tunable circuit elements incorporates an error detector that senses the amplitude or phase of a load current and a controller that adjusts one or more tunable parameters to reduce impedance mismatch. An integrated circuit device suitable for use in a transmitter includes a power amplifier driver circuit and a detector circuit capable of sensing a load current, and a controller circuit that can adjust tunable parameters either within or external to the integrated circuit. By eliminating directional couplers and integrating the detectors and power amplifier drivers, the size, complexity, and cost of wireless transceivers can be reduced, while efficiency and power consumption are improved through the dynamic adjustment of operating points and impedance matching.
Owner:TEXAS INSTR INC

Method and apparatus for antenna tuning

A method for tuning a transmitter in order to improve impedance matching to an antenna or to intermediate radio frequency stages uses an error detector that senses a deviation of the amplitude or phase angle of a load current of a power amplifier driver or of a power amplifier. A controller calculates a correction and dynamically adjusts tunable transmitter parameters, which may include values of components in matching networks or bias voltages in the power amplifier or the power amplifier driver, so as to reduce the deviation and thereby improve the impedance matching. The load current of the power amplifier may alternatively be sensed by measuring the duty cycle of its switching mode power supply. A transmitter having a power amplifier and one or more tunable circuit elements incorporates an error detector that senses the amplitude or phase of a load current and a controller that adjusts one or more tunable parameters to reduce impedance mismatch. An integrated circuit device suitable for use in a transmitter includes a power amplifier driver circuit and a detector circuit capable of sensing a load current, and a controller circuit that can adjust tunable parameters either within or external to the integrated circuit. By eliminating directional couplers and integrating the detectors and power amplifier drivers, the size, complexity, and cost of wireless transceivers can be reduced, while efficiency and power consumption are improved through the dynamic adjustment of operating points and impedance matching.
Owner:TEXAS INSTR INC

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

Frequency synthesizer using a VCO having a controllable operating point, and calibration and tuning thereof

A frequency synthesizer, a calibrator thereof, and an operating controller thereof are described. The synthesizer comprises a main charge pump that drives a voltage controlled oscillator (VCO) through a loop filter. The calibrator includes a second, replica charge pump that can also drive the VCO, but is set up to output only its maximum or minimum analog output control voltage. Since the construction and characteristics of the replica charge pump duplicate the main charge pump, the main charge pump's minimum and maximum analog control outputs can be cloned out to the VCO on demand. A VCO calibration procedure therefore includes switching the VCO to each of its ranges set by a bank of fixed capacitors, and using the replica charge pump to drive the VCO to its minimum and maximum frequency for each range setting. The min-max frequency data is stored in a lookup table, and operational requests to switch to a new channel frequency can be supported with a priori information about which fixed-capacitor range selection will be best. The operating point controller includes a sensor to sense the operating point and a controller that provides a switching input to a switchable bank of capacitors to change the operating point. The change can be determined according to calibration data.
Owner:CISCO SYST WIRELESS NETWORKING AUSTRALIA

Digitally-controlled oscillator with switched-capacitor frequency selection

A digitally-controlled oscillator (DCO) (60), such as may be used in clock generator or clock recovery circuitry in an integrated circuit, is disclosed. The disclosed DCO (60) is a single-stage oscillator including a variable load implemented as a binary-weighted array of switched capacitors (40). Each of capacitors (40) has a plate connected to a common node (X), and a plate that receives a signal corresponding to one bit of a digital control word (DCOCW). The common capacitor node (X) is also connected to the input of a Schmitt trigger (42) that produces the output clock signal (OUTCLK) and a feedback signal that is applied to logic (38, 39) that inverts the common node of the capacitors (40). The switching time at the input of Schmitt trigger (42) depends upon the variable load presented by the array of switched capacitors (40), which is controlled by the digital control word (DCOCW). As a result, the clock signal (OUTCLK) is digitally synthesized by a single stage of the DCO (60). A digital phase-locked loop (PLL) clock generator circuit (50) including a phase detector (64), digital loop filter (62) in combination with the DCO (60), and a programmable frequency divider (66) providing a feedback path from the output of the DCO (60) to the phase detector (64), is also disclosed. The PLL clock generator (50) may be used in an integrated circuit such as a digital signal processor (30) or microprocessor, and is particularly well-suited for use in a battery-powered portable electronic system (200).
Owner:TEXAS INSTR INC
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