Abstract: An RF signal switch circuit that allows connection of any of N radio frequency (RF) input terminals to a switch output port, either in a low loss mode, in a bypass mode, or, optionally, in a signal function mode. Embodiments of the invention allow for both a single switch in the series input path to a target circuit while still having the ability to isolate the bypass path from the target circuit. In the low loss and bypass mode, the circuit simultaneously exhibits low input insertion loss (and thus a low noise factor) and high bypass mode isolation.

Abstract: Embodiments of an RF amplifier include a transistor with a control terminal and first and second current carrying terminals, and a shunt circuit coupled between the first current carrying terminal and a ground reference node. The shunt circuit is an output pre-match impedance conditioning shunt circuit, which includes a first shunt inductance, a second shunt inductance, and a shunt capacitor coupled in series. The first shunt inductance comprises a plurality of bondwires coupled between the first current carrying terminal and the second shunt inductance, and the second shunt inductance comprises an integrated inductor coupled between the first shunt inductance and a first terminal of the shunt capacitor. The shunt capacitor is configured to provide capacitive harmonic control of an output of the transistor.

Abstract: A power amplifier includes an operational amplifier, a ramp generator communicatively coupled to both a first comparator and a second comparator; the first comparator further communicatively coupled to a negative output port of the operational amplifier; the second comparator further communicatively coupled to a positive output port of the operational amplifier; a first inverter communicatively coupled to the first comparator; a second inverter communicatively coupled to the second comparator; wherein the first inverter is communicatively coupled to both a positive input port of the operational amplifier via a first resistor and coupled to a negative input port of the operational amplifier via a fourth resistor; and the second inverter is communicatively coupled to both the positive input port of the operational amplifier via a second resistor and connected to the negative input port of the operational amplifier via a third resistor.

Abstract: A receiving circuit includes a first capacitor connected to a first signal line, a second capacitor connected to a second signal line. A first bias control circuit may convert a common mode voltage of a first received signal provided through the first capacitor to a first voltage level to output a first biased signal. A second bias control circuit may convert a common mode voltage of a second received signal provided through the second capacitor to a second voltage level to output a second biased signal. A balance compensation circuit may receive the first biased signal and the second biased signal, compensate for an offset voltage of the first biased signal based on the second biased signal, and compensate for an offset voltage of the second biased signal based on the first biased signal to output a first differential signal and a second differential signal.

Abstract: A signal processing circuit reduces die size and power consumption for each antenna element. The signal processing circuit includes a first set of ports, a third port, a first path, a second path and a first transistor. The first path is between a first port of the first set of ports and the third port. The second path is between a second port of the first set of ports and the third port. The first transistor is coupled between the first path and the second path. The first transistor is configured to receive a control signal to control the first transistor to adjust an impedance between the first path and the second path.

Abstract: Embodiments of the present invention are directed to an electro-optical device that comprises a substrate, a waveguide structure, and two contact layer portions. The contact layer portions extend side-by-side along a direction of light propagation that is parallel to the substrate. The waveguide structure may guide light along said direction of light propagation. The waveguide structure comprises an optically nonlinear material and interdigitated crosspieces. The crosspieces extend parallel to the substrate from each of said two contact layer portions and transversely to such portions. The optically nonlinear material is in contact with at least portions of the interdigitated crosspieces. Said crosspieces are not in direct contact with each other, forming a composite waveguide core involving an alternating sequence of distinct materials along said propagation direction.

Abstract: Certain aspects of the present disclosure are generally directed to circuitry and techniques for adjusting an audio signal to avoid undesirable system behavior under low alternating-current (AC) line voltage and high volume conditions. For example, certain aspects provide an apparatus for audio amplification. The apparatus generally includes an amplifier, a supply voltage generation circuit having an input coupled to an input voltage node of the apparatus and an output coupled to a supply voltage terminal of the amplifier, the supply voltage generation circuit having a transformer, a primary winding of the transformer being coupled to the input voltage node, a peak voltage detector circuit configured to detect a peak voltage at a secondary winding of the transformer, and a controller circuit configured to adjust an input audio signal of the amplifier based on the detected peak voltage.

Abstract: It is described a modulator apparatus (3) comprising: an input terminal (23) structured to receive an analog electrical signal (x(t)) having an information content to be transmitted; a loop filter structured to receive an error signal (?(t) and provide a filtered signal (s(t)), the loop filter being configured to minimize said error signal (?(t)); a modulator device (10) configured to module the filtered signal (s(t)) and provide a Pulse Width Modulated, PWM, signal (y(t)) to be transmitted including a plurality of pulses having corresponding widths correlated to non-quantized amplitudes of the filtered signal (s(t)); a first pulse width demodulator (11) configured to receive the PWM, signal (y(t)) and provide a demodulated signal (?(t)) and a difference module (12) configured to receive the analog electrical signal (x(t)) and the demodulated signal (?(t)) and provide the error signal (?(t)).

Abstract: An amplifier circuit arrangement and a method for calibrating the same. In an embodiment an amplifier circuit arrangement includes a desired signal path including a differential amplifier for an analog signal having an input side and an output side and an analog-to-digital converter having an output terminal, a first feedback path to calibrate an offset of the desired signal path coupled to differential signal lines at the output side of the differential amplifier and to differential signal lines at the input side of the differential amplifier, the first feedback path including a comparator and at least one counter controlled by an output of the comparator and a second feedback path to calibrate a drift of the desired signal path coupled to the output terminal of the analog-to-digital converter and to the differential signal lines at the input side of the differential amplifier, the second feedback path including an average filter.

Abstract: A power supply apparatus including a signal generator circuit configured to generate a plurality of power supply signals via at least one DC-to-DC converter, the plurality of power supply signals including a first power supply signal on a first output path and a second power supply signal on a second output path that is independent of the first output path, the first power supply signal being different from the second power supply signal. The apparatus includes a switching circuit to provide during a first operating mode, a first combined power supply signal on the first output path based on the first power supply signal and a third power supply signal of the plurality of power supply signals. The switching circuit provides during a second operating mode, a second combined power supply signal on the second output path based on the second power supply signal and the third power supply signal.

Abstract: Some embodiments of the invention include a pre-pulse switching system. The pre-pulsing switching system may include: a power source configured to provide a voltage greater than 100 V; a pre-pulse switch coupled with the power source and configured to provide a pre-pulse having a pulse width of Tpp; and a main switch coupled with the power source and configured to provide a main pulse such that an output pulse comprises a single pulse with negligible ringing. The pre-pulse may be provided to a load by closing the pre-pulse switch while the main switch is open. The main pulse may be provided to the load by closing the main switch after a delay Tdelay after the pre-pulse switch has been opened.

Abstract: An RF signal switch circuit that allows connection of any of N radio frequency (RF) input terminals to a switch output port, either in a low loss mode, in a bypass mode, or, optionally, in a signal function mode. Embodiments of the invention allow for both a single switch in the series input path to a target circuit while still having the ability to isolate the bypass path from the target circuit. In the low loss and bypass mode, the circuit simultaneously exhibits low input insertion loss (and thus a low noise factor) and high bypass mode isolation.

Abstract: A rail balancing circuit is described herein for use with a power supply, the RBC comprising: a circuit adapted to respond to over-voltage and under-voltage conditions in the power supply that comprises a positive rail voltage source and a negative rail voltage source, such that any deviation from a balanced condition between the positive rail voltage source and the negative rail voltage source is substantially instantaneously corrected to bring both the positive and negative rail voltage sources back to the balanced condition.

Abstract: A hearable has an audio amplifier circuit coupled to a speaker as a load. The amplifier circuit has current source drive, which attenuates electromagnetically coupled noise of the speaker. In other instances, the amplifier circuit has a first amplifier mode and a second amplifier mode, wherein in the first amplifier mode the amplifier circuit becomes configured to drive the speaker as a voltage source, and in the second amplifier mode the amplifier circuit becomes configured to drive the speaker as a current source. Control logic varies the amplifier circuit between i) the first amplifier mode for larger amplitudes of the audio signal, and ii) the second amplifier mode for smaller amplitudes of the audio signal. Other aspects are also described and claimed.

Abstract: Described herein are systems configured for inter-band carrier aggregation. Systems include a multiplexing circuit having a switching network and diplexers wherein the switching network is configured to share inductors between multiple paths of the multiplexing circuit. The filters can be designed so that when operated simultaneously (e.g., during multi-band operation) the same inductance can be used allowing the switching network to switch in a particular inductance into the path. The described systems can include an inductance that is coupled to an output port so that when operating in single-band mode, the different paths share the same inductance. Relative to other solutions, the described systems can improve performance (e.g., reduce insertion loss), reduce the number of components in the associated module, reduce manufacturing costs, and the like.

Abstract: A radio frequency (RF) amplifier circuit includes an amplifier device and a first baseband bias circuit. The amplifier device includes a first input configured to receive a first signal to be amplified and a first output configured to output a first amplified signal. The first baseband bias circuit includes an input coupled to the first output of the amplifier device. The first baseband bias circuit includes a first envelope decoupling circuit and a first harmonic decoupling circuit. The first envelope decoupling circuit includes a first bulk capacitor and a first distributed inductor configured to resonate in a baseband frequency range. The first harmonic decoupling circuit includes a second bulk capacitor and a second distributed inductor configured to resonate at a harmonic frequency of the frequency of the first signal received at the input of the amplifier device.

Abstract: A power amplifier circuit includes a power amplifier that amplifies an input signal and outputs the amplified signal from an output terminal thereof, a first filter circuit that has a frequency characteristic that attenuates an Nth-order harmonic of the amplified signal, N that is an integer greater than or equal to 2, and a second filter circuit that has a frequency characteristic that attenuates the Nth-order harmonic of the amplified signal. The first filter circuit includes a first capacitor and a first inductor. The first capacitor and the first inductor are connected in series between the output terminal and ground. The second filter circuit includes a second capacitor and a second inductor. The second capacitor and the second inductor are connected in series between the output terminal and ground.

Abstract: An oscillator, including a resonance circuit, a cross coupled current source circuit, and a positive feedback circuit coupled between the current source circuit and the resonance circuit, where the resonance circuit is configured to generate a differential oscillation signal having a first oscillation frequency, the positive feedback circuit is configured to receive the differential oscillation signal, and amplify a gain of the differential oscillation signal to obtain a differential output oscillation signal, and the current source circuit is configured to provide an adjustable bias current for the resonance circuit and the positive feedback circuit.

Abstract: Disclosed is a passive intermodulation (PIM) test system having a pulsed signal generator configured to generate and apply a pulsed stimulus signal to a device under test. The PIM test system is further configured to measure a power of at least one PIM product generated by a PIM source in the device under test using the pulsed stimulus signal. Also disclosed in a method for evaluating PIM in a device under test, the method includes using a pulsed stimulus signal to measure a power of at least one PIM product generated by a PIM source in the device under test.

Abstract: A boosted audio amplifier system includes a first digital interpolation filter configured to oversample an audio input signal at a first oversampling rate and includes a signal level detector having an input coupled to receive the oversampled audio input signal and configured to produce an audio input level signal. The system further includes a programmable delay buffer having inputs coupled to receive the oversampled audio input signal and a first delay signal. The programmable delay buffer adds a first delay to the oversampled audio input signal to produce a delayed input signal. The system also includes a first processor having inputs coupled to receive a battery voltage level signal, the audio input level signal and the first delay signal. The first processor is configured to produce boost control signals to regulate a boost voltage.

Abstract: Systems and methods for adaptive modulation of MOSFET driver key parameters for improved voltage regulator efficiency and reliability in a voltage regulator may include a power stage. The power stage may include a high side switch including a high side gate, a peak voltage detection circuit, and a high side driver strength modulator circuit. The high side driver strength modulator circuit may determine a high side driver strength level. The high side driver strength modulator circuit may also connect a subset of the set of high side gate drivers to the high side gate based on the high side driver strength level. The high side driver strength modulator circuit may also disconnect a remaining subset of the set of high side gate drivers from the high side gate.

Abstract: An amplifier device includes an input terminal, an output terminal, a first transistor having a control terminal and first and second current-carrying terminals, and a class-J circuit coupled between the second current-carrying terminal of the first transistor and the output terminal and configured to harmonically terminate the first transistor. The class-J circuit may include a first resonator, characterized by a first resonant frequency substantially equal to a second harmonic frequency. The first resonator may be coupled between the second current-carrying terminal and a voltage reference. A shunt inductor that is distinct from the first resonator may be coupled between the second current-carrying terminal and the voltage reference.

Abstract: A new method for amplifying signals having higher bandwidth, lower T.H.D., higher efficiency, smaller circuit size and lower costs in design, has been developed. A clipped signal is amplified to smaller pieces and each smaller part is amplified. Adding clipped amplified signals to each other, the main amplified signal is generated.

Abstract: A method to soft start a charge pump circuit according to embodiments includes enabling switching for a plurality of power transistors, selecting a first switching control signal from a plurality of switching control signals for the selected plurality of power transistors, slowly ramping up a plurality of bootstrap supply voltages associated with the selected plurality of power transistors, driving a gate-to-source voltage of each power transistor of the selected plurality of power transistors at a first predefined level, and determining if the plurality of bootstrap supply voltages are less than a second predefined level. If the plurality of bootstrap supply voltages are less than the second predefined level, the method further includes toggling and thereby selecting a second switching control signal from the plurality of switching control signals for a second selected plurality of power transistors.

Abstract: A system may include a plurality of playback paths comprising an open-loop playback path configured to drive an output load and a closed-loop playback path. The closed-loop playback path may include an outer feedback loop comprising one or more integrators, a quantizer, and an output driver for driving the output load, the outer feedback loop having an outer loop feedback gain and an inner feedback loop comprising the one or more integrators and the quantizer and excluding the output driver, wherein the inner feedback loop has a variable inner loop feedback gain which is adjustable to match the outer loop feedback gain.

Abstract: The present document describes a digital power amplifier configured to provide an amplified output signal at an output port based on an input signal. The power amplifier comprises a drive unit configured to generate a high side drive signal comprising a sequence of pulses for controlling the high side switch and a low side drive signal comprising a sequence of pulses for controlling the low side switch, respectively. The drive signals are generated such that the pulses of the high side drive signal are non-overlapping with regards to the pulses of the low side drive signal, and such that the sequence of pulses of the high side drive signal and the sequence of pulses of the low side drive signal have a reduced fraction of energy from higher order harmonics compared to a sequence of rectangular shaped pulses.

Abstract: Systems and methods for a distributed antenna network are provided. One system includes a plurality of antenna modules coupled via a communication line, with each antenna module configured to be switched between a through state and a connected state using radio-frequency identification (RFID) control signals. The system further includes a plurality of antennas, with each antenna connected to a corresponding antenna module. A controller is coupled to the communication line and configured to transmit RFID control signals to the plurality of antenna modules to selectively activate one of the antenna modules by switching the antenna module to the connected state to thereby activate an antenna connected to the antenna module in the connected state.

Abstract: An amplifier may include a first stage configured to receive an input signal at an amplifier input and generate an intermediate signal which is a function of the input signal, and a final output stage configured to generate an output signal which is a function of the intermediate signal at an amplifier output, and a signal feedback network coupled between the amplifier output and input. The final output stage may be switchable among a plurality of modes including at least a first mode in which the final output stage generates the output signal as a modulated output signal which is a function of the intermediate signal, and a second mode in which the final output stage generates the output signal as an unmodulated output signal which is a function of the intermediate signal. Structure of the feedback network and the first stage may remain static when switching between modes.

Abstract: The present disclosure relates to a signal processing apparatus capable of reducing a circuit scale when transmitting and receiving a signal from an antenna. A first n-type MOS transistor amplifies a transmission signal to be transmitted from the antenna. A second n-type MOS transistor supplies a reception signal to be received from the antenna to a reception circuit. The first n-type MOS transistor and the second n-type MOS transistor are connected to the antenna in series. Furthermore, the reception circuit is connected to a contact between the first n-type MOS transistor and the second n-type MOS transistor. The present disclosure is capable of being applied to, for example, a radio transceiver.

Abstract: A system includes a class D amplifier and a current steering digital-to-analog converter (DAC) directly connected to the class D amplifier. The system also includes a common mode servo circuit coupled to a node interconnecting the current steering DAC to the class D amplifier. The common servo circuit amplifies a difference between a common mode signal determined from the node and a reference voltage and generates a feedback current to the node based on the amplified difference. A feed-forward common-mode compensation circuit is included to reduce an alternating current (AC) ripple from the class D amplifier. The feed-forward common-mode compensation circuit includes first and second resistors coupled to respective outputs of the class D amplifier. A current mirror is coupled to the first and second resistors and is configured to sink a current from the node to ground that approximates a common mode feedback current of the class D amplifier.

Abstract: Described is an apparatus which comprises: a driver comprising a push-pull transmitter; a first circuitry to sense variation in a power supply; and a second circuitry coupled to the first circuitry and to the driver, the second circuitry to generate a code according to an output of the first circuitry, wherein the code is provided to the driver to adjust a performance parameter of the driver.

Abstract: A class-D amplifier includes an output driver, a pulse width modulator, an integrator, and duty cycle control circuitry. The output driver is configured to drive a loudspeaker. The pulse width modulator is coupled to the output driver. The integrator is coupled to the pulse width modulator. The duty cycle control circuitry is coupled to the integrator. The duty cycle control circuitry is configured to monitor amplitude of output signal of the integrator, and change an average duty cycle of signal at an output of the output driver as a function of the amplitude.

Abstract: Flexible subcutaneous implantable medical device (IMD), including an elongated and flexible body, a plurality of electronic components, at least one rechargeable battery, at least one antenna, at least one lead and at least one transition unit, the antenna for receiving and transmitting electromagnetic radiation and the lead for providing an electric shock, wherein the elongated and flexible body is structured from a plurality of units, wherein a first one of the plurality of units encapsulates the rechargeable battery, wherein each one of the other plurality of units respectively encapsulates a respective one of the plurality of electronic components, wherein the antenna is positioned in the transition unit, wherein the transition unit is covered with a biocompatible polymer, wherein the antenna receives electromagnetic radiation for recharging the rechargeable battery and wherein the antenna includes a copper coil having a generally cylindrical shape.

Abstract: A class-D amplifier of an embodiment includes: a PWM modulator configured to output a PWM pulse based on an input signal; a first output transistor group, in which a connection point of complementarily operated two first output transistors is an output end; a second output transistor group, in which a connection point of complementarily operated two second output transistors is connected to the connection point of the first transistors; a driver circuit capable of driving the first output transistors and the second output transistors of the first and second output transistor groups, based on the PWM pulse from the PWM modulator; and a control circuit configured to generate a control signal for operating at least one of the first output transistor group and the second output transistor group.

Abstract: A method is provided for guiding locomotion speed in a human or other animal subject. The method comprises: estimating the subject's actual locomotion speed using one or more sensors to thereby obtain a measured speed; determining an error comprising a difference between a desired speed and the measured speed; and outputting, to the subject, a stimulus frequency signal wherein the stimulus frequency signal is based on the error in such a manner that when the subject ambulates in a manner that matches a frequency of the stimulus frequency signal, the subject's actual speed controllably tracks the desired speed.

Abstract: A multi-level class D audio power amplifier for supplying an N-level drive signal to a loudspeaker. The multi-level class D audio power amplifier includes a switching matrix having controllable semiconductor switches where the switching matrix include at least (N?2) switch inputs, coupled to respective ones of (N?2) DC input voltage nodes, and at least 2*(N?2) switch outputs coupled to respective ones of 2*(N?2) intermediate nodes of a first output driver. A control circuit is configured to sequentially connect each of the (N?2) DC input voltages to a predetermined set of nodes of the 2*(N?2) intermediate nodes of the first output driver via the switching matrix in accordance with one or more of the 2*(N?1) modulated control signals of the first output driver. N is a positive integer larger than or equal to 3.

Abstract: Methods and apparatus relate to a bidirectional differential interface having a voltage-mode transmit driver architecture formed of multiple selectively enabled slices for coarse output resistance impedance matching. In an illustrative example, the transmit driver may include a programmable resistance for fine-tuning to impedance match the output resistance for transmit operation. During receive operation, protective voltage may be proactively applied to gates of drive transistors, for example, to minimize voltage stresses applied by external signal sources. Some implementations may automatically float the sources of the drive transistors, for example, to prevent back-feeding externally driven signal currents during receive mode operations. The transmit driver may have programmable voltage swing on, for example, the upper and/or lower bounds to enhance compatibility. A programmable common mode voltage node may be selectively applied, for example, through common mode resistors for receive mode operations.

Abstract: An amplifier includes a first transistor coupled to a first voltage source node and a second transistor coupled to a second voltage source node. The first and second transistors also couple together at an intermediate node. The amplifier further includes a third transistor coupled to the intermediate node and a fourth transistor coupled to the third transistor at a positive output node of the amplifier. Further, the amplifier includes a fifth transistor coupled to the intermediate node and a sixth transistor coupled to the fifth transistor at a negative output node of the amplifier.

Abstract: Aspects are directed to an amplifier circuit including a signal processing circuit and a calibration circuit. In certain specific embodiments, the signal processing circuit includes a signal combiner and a closed-loop feedback path, and the signal processing circuit is designed to provide a loop transfer function for a derived signal partly representing contributions from an audio input signal, a control or pilot signal having a target frequency range, and a calibration signal. The signal combiner is designed to combine aspects of the control or pilot signal and aspects of the audio input signal, and the calibration circuit is designed to adjust an effective gain of the derived signal in response to whether a unity-gain frequency of a signal in the closed-loop feedback path, as provided via the loop transfer function, is higher or lower than the target frequency range.

Abstract: A power amplifier using an equivalent transformer is provided. The power amplifier includes amplifiers and T lines having first terminals connected to the amplifiers and second terminals connected to output sides. Accordingly, powers are combined using the equivalent transformer in the power amplifier, such that an insertion loss can be reduced and thus degradation of output power efficiency can be prevented.

Abstract: Resistor mismatch may be digitally compensated based on a known resistor mismatch, power supply information, and/or other operating parameters of the amplifier. The digital compensation may be applied to the digital input signal before conversion for processing and amplification in the analog domain. An amplifier with digital compensation for resistor mismatch may be used in a class-D amplifier with a closed loop and feedforward feedback. A class-D or other amplifier with digital compensation may be integrated with electronic devices such as mobile phones.

Abstract: A class-D amplifier includes measurement of speaker current via the low-side drive transistors of the amplifier. In one embodiment, a class-D amplifier includes two high-side transistors, two low-side transistors, a first sense resistor, a second sense resistor, and a sigma delta analog to digital converter (?? ADC). The two high-side transistors and two low-side transistors are connected as a bridge to drive a bridge tied speaker. The first sense resistor is connected between a first of the low-side transistors and a low-side reference voltage. The second sense resistor is connected between a second of the low-side transistors and the low-side reference voltage. The ?? ADC is coupled to the bridge to measure voltage across the first sense resistor and the second sense resistor.

Abstract: The present invention relates to a bi-directional DC-DC converter comprising: a first terminal, a second terminal, a transformer circuit, a first high voltage side coupled to said first terminal, and a second low voltage side coupled to said second terminal; wherein said first high voltage side and said second low voltage side are coupled to each other by means of said transformer circuit, and said first high voltage side comprises a resonant tank circuit coupled between a first bridge circuit of said first high voltage side and a high voltage side of said transformer circuit. Furthermore, the invention also relates to a system comprising at least two such bi-directional DC-DC converters.

Abstract: An audio amplifier circuit for driving an electro-acoustic transducer, which is bridged transless (BTL)-connected to the audio amplifier circuit, in a filterless manner, including: a class D amplifier including a high side transistor and a low side transistor; a high side driver configured to drive the high side transistor; and a low side driver configured to drive the low side transistor, as a pair, wherein the low side driver is configured so that a time for turning off the low side transistor by the low side driver is longer than that for turning off the high side transistor by the high side driver.

Abstract: Various embodiments disclose a method for fabricating vertical transistors. In one embodiment, a structure is formed comprising at least a first substrate, an insulator layer on the substrate, a first doped layer on the insulator layer, at least one fin structure in contact with the doped layer, a dielectric layer surrounding a portion of the fin structure, a gate layer on the dielectric layer, a second doped layer in contact with the fin structure, a first contact area in contact with the second doped layer, and at least a first interconnect in contact with the first contact area. The structure is flipped bonded to a second substrate. The first substrate and the insulator layer are removed to expose the first doped layer. A second contact area is formed in contact with the first doped layer. At least a second interconnect is formed in contact with the second contact area.

Abstract: Aspects of this disclosure relate to efficient power amplifiers, such as class-F power amplifiers. A power amplifier transistor can provide an amplified RF signal. A termination can be coupled to an output of the power amplifier transistor and configured to provide a short circuit at a second harmonic. In some instances, the termination circuit can provide an open circuit at a third harmonic. A resonant circuit can be coupled to the output terminal of the power amplifier transistor and configured to provide an open circuit at the third harmonic. In certain embodiments, an input termination circuit coupled to an input terminal of the power amplifier transistor can provide a short circuit at the second harmonic. The power amplifiers of this disclosure can be implemented, for example, in envelope tracking applications.

Abstract: Systems and method for improving operation of a radio frequency system are provided. One embodiment includes a switching power amplifier that outputs an amplified analog electrical signal based on an input electrical signal and voltage of an envelope voltage supply rail. The switching power amplifier includes a first transistor with a gate that receives the input electrical signal, a source electrically coupled to the envelope voltage supply rail, and a drain electrically coupled to an output of the switching power amplifier; a second transistor with a gate that receives the input electrical signal, a source electrically coupled to ground, and a drain electrically coupled to the output; and a third transistor with a gate that receives the input electrical signal, a drain electrically coupled to the envelope voltage supply rail, and a source electrically coupled to an output of another switching power amplifier.

Abstract: A boost DC-DC power converter comprising a semiconductor switch arrangement comprising a plurality of series connected semiconductor switches. A first capacitor is connected between a first intermediate node of a first leg of the semiconductor switch arrangement and a second intermediate node of a second leg of the semiconductor switch arrangement. A control circuit is coupled to respective control terminals of the plurality of semiconductor switches. A load sensor is configured to detect a load current and/or a load voltage of a load circuit connectable to at least a first DC output voltage of the DC-DC power converter. The control circuit being further configured to adjusting one or more operational parameters of the boost DC-DC power converter based on the detected load current and/or load voltage.

Abstract: A power amplifier device includes first and second pairs of semiconductor switches, transformers, and a zero-crossing detection circuit for detecting a zero voltage crossing of an analog input signal. The switches of the first pair receive a respective positive and negative component of the input signal. The transformers store energy from the positive and negative components, respectively. Each transformer releases accumulated energy when the respective switch of the first pair turns off The switches of the second pair have opposite switching states and are connected between a respective transformer and a load, e.g., a transducer, speak, or motor. Each switch receives released energy from the respective transformer. A switching state of each switch of the second pair changes in response to a detected zero voltage crossing of the input signal to transfer the released energy to the load. A system includes the device and the load.

Abstract: A power amplifier includes an input amplifier, a comparator, a switching circuit, an output filter and a feedback filter. The input amplifier receives an input signal of the power amplifier at a positive input of the input amplifier and an output signal of the feedback filter at a negative input of the input amplifier. The input amplifier has a capacitive feedback from an output of the input amplifier to the negative input of the input amplifier. The comparator receives the output signal of the input amplifier at a positive input of the comparator and the output signal of the feedback filter at a negative input of the comparator. The comparator provides a control signal based on a comparison between signal levels of the signals at the positive and the negative inputs of the comparator.