Abstract: Techniques for controlling transmit power and adjusting an antenna tuning network of a wireless device are disclosed. In an exemplary design, an apparatus (e.g., a wireless device or a circuit module) includes a directional coupler and at least one detector. The directional coupler receives an input radio frequency (RF) signal at a first port, provides an output RF signal at a second port, and provides a coupled RF signal at a third port. The detector(s) receive at least one RF signal on at least one port of the directional coupler, measure the at least one RF signal, and provide measurements that are used to control the transmit power of the wireless device and adjust an antenna tuning network. For example, the measurements may be used to determine incident power, reflected power, delivered power, etc., which may be used to control the transmit power and/or adjust the antenna tuning network.

Abstract: Tunable matching circuits for power amplifiers are described. In an exemplary design, an apparatus may include a power amplifier and a tunable matching circuit. The power amplifier may amplify an input RF signal and provide an amplified RF signal. The tunable matching circuit may provide output impedance matching for the power amplifier, may receive the amplified RF signal and provide an output RF signal, and may be tunable based on at least one parameter effecting the operation of the power amplifier. The parameter(s) may include an envelope signal for the amplified RF signal, an average output power level of the output RF signal, a power supply voltage for the power amplifier, IC process variations, etc. The tunable matching circuit may include a series variable capacitor and/or a shunt variable capacitor. Each variable capacitor may be tunable based on a control generated based on the parameter(s).

Abstract: Techniques for adaptively tuning an impedance matching circuit are disclosed. In an aspect, the impedance matching circuit is pre-characterized. The performance of the impedance matching circuit is determined for multiple settings of the impedance matching circuit, stored in memory, and used to tune the impedance matching circuit. In another aspect, the impedance matching circuit is tuned based on measurements for one or more parameters such as delivered power, return loss, power amplifier current, antenna/load impedance, etc. In an exemplary design, an apparatus includes a memory and a control unit. The memory stores information for multiple settings of an impedance matching circuit. The control unit selects one of the multiple settings of the impedance matching circuit based on the information for the multiple settings and measurements for the impedance matching circuit. The impedance matching circuit performs impedance matching for a load circuit (e.g., an antenna) based on the selected setting.

Abstract: Reconfigurable impedance matching circuits with multiple configurations are disclosed. A reconfigurable impedance matching circuit may be implemented with a set of reactive elements (e.g., inductors and/or capacitors) and a set of switches. Different configurations may be obtained with different settings of the switches and may be associated with different impedance tuning curves. This may enable the reconfigurable impedance matching circuit to provide better impedance matching for a load circuit (e.g., an antenna). In an exemplary design, the reconfigurable impedance matching circuit includes at least one variable reactive element configured to tune the impedance of the reconfigurable impedance matching circuit in order to provide better impedance matching. In an exemplary design, the reconfigurable impedance matching circuit may include at least one reconfigurable reactive element, each of which can be connected as a series element or a shunt element.

Abstract: A multi-mode multi-band power amplifier (PA) module is described. In an exemplary design, the PA module includes multiple power amplifiers, multiple matching circuits, and a set of switches. Each power amplifier provides power amplification for its input signal when selected. Each matching circuit provides impedance matching and filtering for its power amplifier and provides a respective output signal. The switches configure the power amplifiers to support multiple modes, with each mode being for a particular radio technology. Each power amplifier supports at least two modes. The PA module may further include a driver amplifier and an additional matching circuit. The driver amplifier amplifies an input signal and provides an amplified signal to the power amplifiers. The additional matching circuit combines the outputs of other matching circuits and provides an output signal with higher output power. The driver amplifier and the power amplifiers can support multiple output power levels.

Abstract: Exemplary embodiments disclosed are directed to power and impedance measurement circuits that may be used to measure power and/or impedance are described. A measurement circuit may include a sensor and a computation unit. The sensor may sense (i) a first voltage signal across a series circuit coupled to a load to obtain a first sensed signal and (ii) a second voltage signal at a designated end of the series circuit to obtain a second sensed signal. The sensor may mix (i) a first version of the first sensed signal with a first version of the second sensed signal to obtain a first sensor output and (ii) a second version of the first sensed signal with a second version of the second sensed signal to obtain a second sensor output. The computation unit may determine the impedance and/or delivered power at the designated end of the series circuit based on the sensor outputs.

Abstract: Certain aspects of the present disclosure propose a method and an apparatus for antenna tuning and transmit path selection in an RF system. A method may include antenna diversity path selection by (optionally) diagnosing damaged antennas, tuning antennas, and selecting an antenna with better performance. Embodiments can be used in wireless radio-frequency (RF) front-ends. Other aspects, embodiments, and features are also claimed and described.

Abstract: Techniques for controlling transmit power and adjusting an antenna tuning network of a wireless device are disclosed. In an exemplary design, an apparatus (e.g., a wireless device or a circuit module) includes a directional coupler and at least one detector. The directional coupler receives an input radio frequency (RF) signal at a first port, provides an output RF signal at a second port, and provides a coupled RF signal at a third port. The detector(s) receive at least one RF signal on at least one port of the directional coupler, measure the at least one RF signal, and provide measurements that are used to control the transmit power of the wireless device and adjust an antenna tuning network. For example, the measurements may be used to determine incident power, reflected power, delivered power, etc., which may be used to control the transmit power and/or adjust the antenna tuning network.

Abstract: Certain aspects of the present disclosure propose a method and an apparatus for antenna tuning and transmit path selection in an RF system. A method may include antenna diversity path selection by (optionally) diagnosing damaged antennas, tuning antennas, and selecting an antenna with better performance. Embodiments can be used in wireless radio-frequency (RF) front-ends. Other aspects, embodiments, and features are also claimed and described.

Abstract: A wireless device configured for optimizing a delivered power is described. The wireless device includes a filter duplexer or switch coupled to a transmitter and a receiver. The wireless device also includes a power/impedance detector coupled to the filter duplexer or switch. The power/impedance detector includes a directional coupler. An antenna is coupled to the power/impedance detector. Other aspects, embodiments and features are also claimed and described.

Abstract: Exemplary techniques for performing impedance matching are described. In an exemplary embodiment, the apparatus may include an amplifier (e.g., a power amplifier) coupled to first and second matching circuits. The first matching circuit may include multiple stages coupled to a first node and may provide input impedance matching for the amplifier. The second matching circuit may include multiple stages coupled to a second node and may provide output impedance matching for the amplifier. At least one switch may be coupled between the first and second nodes and may bypass or select the amplifier. The first and second nodes may have a common impedance. The apparatus may further include a second amplifier coupled in parallel with the amplifier and further to the matching circuits. The second matching circuit may include a first input stage coupled to the amplifier, a second input stage coupled to the second amplifier, and a second stage coupled to the two input stages via switches.

Abstract: Techniques for adaptively tuning an impedance matching circuit are disclosed. In an aspect, the impedance matching circuit is pre-characterized. The performance of the impedance matching circuit is determined for multiple settings of the impedance matching circuit, stored in memory, and used to tune the impedance matching circuit. In another aspect, the impedance matching circuit is tuned based on measurements for one or more parameters such as delivered power, return loss, power amplifier current, antenna/load impedance, etc. In an exemplary design, an apparatus includes a memory and a control unit. The memory stores information for multiple settings of an impedance matching circuit. The control unit selects one of the multiple settings of the impedance matching circuit based on the information for the multiple settings and measurements for the impedance matching circuit. The impedance matching circuit performs impedance matching for a load circuit (e.g., an antenna) based on the selected setting.

Abstract: Reconfigurable impedance matching circuits with multiple configurations are disclosed. A reconfigurable impedance matching circuit may be implemented with a set of reactive elements (e.g., inductors and/or capacitors) and a set of switches. Different configurations may be obtained with different settings of the switches and may be associated with different impedance tuning curves. This may enable the reconfigurable impedance matching circuit to provide better impedance matching for a load circuit (e.g., an antenna). In an exemplary design, the reconfigurable impedance matching circuit includes at least one variable reactive element configured to tune the impedance of the reconfigurable impedance matching circuit in order to provide better impedance matching. In an exemplary design, the reconfigurable impedance matching circuit may include at least one reconfigurable reactive element, each of which can be connected as a series element or a shunt element.

Abstract: A method for measuring non-linear characteristics of a power amplifier is described. A calibration waveform is calculated during a testing procedure period. Amplitude characteristics of the calibration waveform at the output of the power amplifier are measured during the testing procedure period. Phase characteristics of the calibration waveform at the output of the power amplifier are measured during the testing procedure period. Pre-distortion techniques are configured based on the amplitude characteristics and the phase characteristics to be used during a normal operation period of a transmitter.

Abstract: Transmitters supporting multiple modulation modes and/or multiple frequency bands are described. A transmitter may perform large signal polar modulation, small signal polar modulation, and/or quadrature modulation, which may support different modulation schemes and systems. Circuit blocks may be shared by the different modulation modes to reduce cost and power. For example, a single modulator and a single power amplifier may be used for small signal polar modulation and quadrature modulation. The transmitter may apply pre-distortion to improve performance, to allow a power amplifier to support multiple frequency bands, to allow the power amplifier to operate at higher output power levels, etc. Envelope and phase distortions due to non-linearity of the power amplifier may be characterized for different input levels and different bands and stored at the transmitter.

Abstract: A method for controlling the voltage of signals used to control power amplifiers is described. A first multiplexer and a second multiplexer are set to an enabling signal. The first multiplexer is on a first integrated circuit and the second multiplexer is on a second integrated circuit. A command is written to the first multiplexer to set the first multiplexer to one of a plurality of control signals used to control a power amplifier. A command is written to the second multiplexer to select one of the plurality of control signals that maps to the first multiplexer. The second integrated circuit is connected to a power supply.

Abstract: Methods and apparatus for amplifier AM and PM predistortion and autocalibration. AM and PM amplifier distortion can be corrected using predistortion. The AM and PM distortion characteristics of the amplifier are determined using an autocalibration technique. The amplifier characteristics can be stored in distinct look up tables. Alternatively, the inverse of the amplifier characteristics can be stored in distinct look up tables. Signals that are to be amplified are characterized in polar format having a phase component with a normalized magnitude and a magnitude component. The phase component can be predistorted by applying the inverse of the PM distortion characteristics to the signal. Similarly, the magnitude component can be predistorted by applying the inverse of the AM distortion characteristics to the signal. The predistorted phase component can be amplified using the previously characterized amplifier.

Abstract: Exemplary techniques for performing impedance matching are described. In an exemplary embodiment, the apparatus may include an amplifier (e.g., a power amplifier) coupled to first and second matching circuits. The first matching circuit may include multiple stages coupled to a first node and may provide input impedance matching for the amplifier. The second matching circuit may include multiple stages coupled to a second node and may provide output impedance matching for the amplifier. At least one switch may be coupled between the first and second nodes and may bypass or select the amplifier. The first and second nodes may have a common impedance. The apparatus may further include a second amplifier coupled in parallel with the amplifier and further to the matching circuits. The second matching circuit may include a first input stage coupled to the amplifier, a second input stage coupled to the second amplifier, and a second stage coupled to the two input stages via switches.

Abstract: Exemplary embodiments disclosed are directed to power and impedance measurement circuits that may be used to measure power and/or impedance are described. A measurement circuit may include a sensor and a computation unit. The sensor may sense (i) a first voltage signal across a series circuit coupled to a load to obtain a first sensed signal and (ii) a second voltage signal at a designated end of the series circuit to obtain a second sensed signal. The sensor may mix (i) a first version of the first sensed signal with a first version of the second sensed signal to obtain a first sensor output and (ii) a second version of the first sensed signal with a second version of the second sensed signal to obtain a second sensor output. The computation unit may determine the impedance and/or delivered power at the designated end of the series circuit based on the sensor outputs.

Abstract: Tunable matching circuits for power amplifiers are described. In an exemplary design, an apparatus may include a power amplifier and a tunable matching circuit. The power amplifier may amplify an input RF signal and provide an amplified RF signal. The tunable matching circuit may provide output impedance matching for the power amplifier, may receive the amplified RF signal and provide an output RF signal, and may be tunable based on at least one parameter effecting the operation of the power amplifier. The parameter(s) may include an envelope signal for the amplified RF signal, an average output power level of the output RF signal, a power supply voltage for the power amplifier, IC process variations, etc. The tunable matching circuit may include a series variable capacitor and/or a shunt variable capacitor. Each variable capacitor may be tunable based on a control generated based on the parameter(s).