Abstract: A power management circuit operable with low battery is provided. The power management circuit is configured to generate a time-variant average power tracking (APT) voltage based on a battery voltage supplied by a voltage source (e.g., battery). In examples disclosed herein, the power management circuit can be configured to remain operable when the battery voltage drops below a low battery threshold. Specifically, the power management circuit maintains the time-variant APT voltage at a constant level in response to the battery voltage dropping below the low battery threshold to thereby avoid drawing a rush current from the voltage source. As a result, a wireless device employing the power management circuit can remain operable with low battery to continue to support critical applications.

Abstract: A target voltage circuit for fast voltage switching is provided. The target voltage circuit is configured to generate a time-variant target voltage(s) to thereby cause a power management circuit to generate a time-variant voltage(s) for a power amplifier circuit. In embodiments disclosed herein, the target voltage circuit receives a number of data signals (e.g., from a transceiver circuit via a parallel bus) that collectively represent a digital target voltage word and maps the digital target voltage word to a target voltage(s). By receiving the digital target voltage word corresponding to the target voltage(s) via the parallel bus, as opposed to directly receiving the target voltage(s) via a serial bus, it is possible to reduce transmission delay. As a result, the power management circuit will be able to switch the time-variant voltage(s) from one voltage level to another based on the target voltage(s) within a defined temporal limit.

Abstract: An apparatus that includes a tracking amplifier having an amplifier output terminal coupled to an output voltage node and an envelope input terminal configured to receive an envelope signal of a radio frequency signal is disclosed. A multi-level voltage converter has a switched voltage terminal coupled to the output voltage node and a converter control input terminal configured to receive a converter control signal. A control signal multiplexer has a converter control output terminal coupled to the converter control input terminal, a first converter signal input terminal configured to receive a first converter control signal corresponding to a lower envelope modulation bandwidth, a second converter signal input terminal configured to receive a second converter control signal corresponding to a higher envelope modulation bandwidth, and a converter control signal selector terminal configured to receive a control selector signal for selecting between the first and second converter control signals.

Abstract: A power management circuit operable to reduce rush current is provided. The power management circuit is configured to provide a time-variant voltage(s) to a power amplifier(s) for amplifying a radio frequency (RF) signal(s). Notably, a variation in the time-variant voltage(s) can cause a rush current that is proportionally related to the variation of the time-variant voltage(s). To reduce the rush current, the power management circuit is configured to maintain the time-variant voltage(s) at a non-zero standby voltage level when the power amplifier(s) is inactive. When the power amplifier(s) becomes active and the time-variant voltage(s) needs to be raised or reduced from the non-zero standby voltage level, the rush current will be smaller as a result of reduced variation in the time-variant voltage(s). As such, it is possible to prolong the battery life in a device employing the power management circuit.

Abstract: A power management circuit for fast average power tracking (APT) voltage switching is provided. The power management circuit includes a primary voltage circuit configured to generate an APT voltage based on an APT target voltage. However, the primary voltage circuit may be inherently slow in ramping up the APT voltage to the APT target voltage. As such, a secondary voltage circuit is provided in the power management circuit to help drive the APT voltage to a desired level by a defined temporal limit. Once the APT voltage reaches the desired level, the secondary voltage circuit will automatically shut off, while the primary voltage circuit continues operating at a selected duty cycle to maintain the APT voltage at the APT target voltage. By utilizing the secondary voltage circuit to quickly drive up the APT voltage, the power management circuit is capable of supporting dynamic power control under stringent switching delay budget.

Abstract: An average power tracking (APT) power management circuit is provided. The APT power management circuit is configured to generate a first APT voltage(s) for a first power amplifier(s) and a second APT voltage(s) for a second power amplifier(s). The APT power management circuit further includes a pair of switcher circuits that can generate a pair of reference voltages. Depending on various operating scenarios of the APT power management circuit, it is possible to selectively output any of the reference voltages as any one or more of the first APT voltage(s) and the second APT voltage(s). As such, it is possible to flexibly configure the APT power management circuit to support the various operating scenarios based on a minimum possible number of the switcher circuits, thus helping to reduce footprint and cost of the APT power management circuit.

Abstract: A Doherty amplifier system is disclosed with a carrier amplifier configured to amplify a first portion of a radio frequency (RF) signal. A peaking amplifier with a peaking output is configured to amplify a second portion of the RF signal when it is above a power level threshold. A first inductor is coupled between the main output and a first middle node, and a second inductor is coupled between the first middle node and the peaking output. The first inductor and the second inductor are configured to have a first magnetic coupling to form a first impedance inverter. A third inductor is coupled between the peaking output and a second middle node, and a fourth inductor is coupled between the second middle node and an RF signal output. The third inductor and the fourth inductor are configured to have a second magnetic coupling to form a second impedance inverter.

Abstract: An envelope tracking (ET) circuit and related power amplifier apparatus is provided. An ET power amplifier apparatus includes an ET circuit and a number of amplifier circuits. The ET circuit is configured to provide a number of ET modulated voltages to the amplifier circuits for amplifying concurrently a number of radio frequency (RF) signals. The ET circuit includes a target voltage circuit for generating a number of ET target voltages adapted to respective power levels of the RF signals and/or respective impedances seen by the amplifier circuits, a supply voltage circuit for generating a number of constant voltages, and an ET voltage circuit for generating the ET modulated voltages based on the ET target voltages and a selected one of the constant voltages. By employing a single ET circuit, it may be possible to reduce the footprint and improve heat dissipation of the ET power amplifier apparatus.

Abstract: The present disclosure relates to a dual-modulation power management circuit (PMC), which includes a first tracking amplifier coupled to a first voltage port and configured to contribute to a first modulated voltage at the first voltage port, a second tracking amplifier coupled to a second voltage port and configured to contribute to a second modulated voltage at the second voltage port, a charge pump, a power inductor, and a low-dropout (LDO) switch unit. Herein, the power inductor is configured to induce an output current, which is based on a boosted voltage generated by the charge pump, toward the first voltage port. A first portion of the output current is eligible to flow through the LDO switch unit from the first voltage port to the second voltage port. The first modulated voltage is not smaller than the second modulated voltage over time.

Abstract: Various arrangements for electrically coupling the electrodes of coupled resonator structures (CRSes) to form unique two- and three-terminal devices as well as the use of such CRSes in filter networks are disclosed.

Abstract: A zero-output coupled resonator filter (ZO-CRF) and related radio frequency (RF) filter circuit are provided. In examples discussed herein, the ZO-CRF can be configured to function as a shunt resonator(s) in an RF filter circuit (e.g., a ladder filter circuit). The ZO-CRF includes a first resonator and a second resonator that are coupled to each other via a coupling layer. The first resonator and the second resonator receive a first voltage and a second voltage, respectively. The first voltage and the second voltage can be configured in a number of ways to cause the ZO-CRF to resonate at different resonance frequencies. As such, it may be possible to modify resonance frequency of the ZO-CRF in an RF filter circuit based on signal connection. As a result, it may be possible to reduce total inductance of the RF filter circuit, thus helping to reduce footprint of the RF filter circuit.

Abstract: Disclosed is a radio frequency multiplexer having an M number of multiplexer branches each having an outer port terminal coupled to a common outer node, wherein M is a positive counting number. Each of the M number of multiplexer branches comprises a multi-bandpass filter configured to filter an N number of bands multiplexed by the radio frequency multiplexer to pass an individual group of N/M bands, wherein N is a positive counting number greater than one and equal to a total number of bands to be multiplexed. Each of the M number of multiplexer branches further includes an N/M number of resonator branches each having a band port terminal configured to pass a single band and an inner branch terminal coupled to an inner port terminal of the multi-bandpass filter at a common inner node.

Abstract: A multi-radio access technology (RAT) envelope tracking (ET) amplifier apparatus is provided. The multi-RAT ET amplifier apparatus may be configured to enable concurrent communication of at least two radio frequency (RF) signals associated with at least two different RATs. Specifically, the multi-RAT ET amplifier apparatus includes an ET integrated circuit (IC) (ETIC) and a distributed ETIC (DETIC) configured to generate respective ET voltages for amplifying the two RF signals. In addition, the DETIC can be configured to utilize certain circuit(s) in the ETIC to help reduce a footprint of the DETIC. By amplifying the two different RF signals based on the respective ET voltages and sharing certain circuit(s) between the ETIC and the DETIC, it may be possible to improve overall efficiency and heat dissipation in the multi-RAT ET amplifier apparatus concurrent to reducing the footprint of the DETIC.

Abstract: An envelope tracking (ET) apparatus is provided. The ET apparatus includes an amplifier array(s) configured to amplify a radio frequency (RF) signal(s) based on an ET voltage(s). The ET apparatus also includes a distributed voltage amplifier (DVA) circuit(s), which may be co-located with the amplifier array(s) to help reduce trace inductance between the DVA circuit(s) and the amplifier array(s), configured to generate the ET voltage(s) based on an ET target voltage(s). The ET apparatus further includes a signal processing circuit configured to receive an analog signal(s) corresponding to the RF signal(s) and generates the ET target voltage(s) based on the analog signal. By employing a single signal processing circuit to generate the ET target voltage(s) for the amplifier array(s), it may be possible to reduce a footprint of the ET apparatus without compromising efficiency and/or increasing heat dissipation of the amplifier array(s).

Abstract: A fast-switching average power tracking (APT) power management integrated circuit (PMIC) is provided. The fast-switching APT PMIC includes a voltage amplifier(s) and an offset capacitor(s) having a small capacitance (e.g., between 10 nF and 200 nF). The voltage amplifier(s) is configured to generate an initial APT voltage(s) based on an APT target voltage(s) and the offset capacitor(s) is configured to raise the initial APT voltage(s) by an offset voltage(s) to generate an APT voltage(s). In embodiments disclosed herein, the offset voltage(s) is modulated based on the APT target voltage(s). Given the small capacitance of the offset capacitor(s), it is possible to adapt the offset voltage(s) fast enough to thereby change the APT voltage(s) within a predetermined temporal limit (e.g., 0.5 ?s). As a result, the fast-switch APT PMIC can enable a power amplifier(s) to support dynamic power control with improved linearity and efficiency.

Abstract: A transmitter apparatus that performs beamforming with phase correction uses power detectors present between power amplifiers (PAs) and antennas are used to measure power amplitudes on at least two transmission paths. The sum and difference of these amplitudes are then evaluated to determine a phase difference therebetween. A phase of one signal contributing to the sum and difference may be modified until the sum and difference are the same. Based on an amount of phase modification, a correction signal may be sent to a beamforming circuit to provide phase correction during beamforming.

Abstract: A wire-based microelectromechanical systems (MEMS) apparatus is provided. In examples discussed herein, the wire-based MEMS apparatus includes a MEMS control bus and at least one passive MEMS switch circuit. The passive MEMS switch circuit is configured to close a MEMS switch(es) by generating a constant voltage(s) that exceeds a defined threshold voltage (e.g., 30-50 V). In a non-limiting example, the passive MEMS switch circuit can generate the constant voltage(s) based on a radio frequency (RF) voltage(s), which may be harvested from an RF signal(s) received via the MEMS control bus. In this regard, it may be possible to eliminate active components and/or circuits from the passive MEMS switch circuit, thus helping to reduce leakage and power consumption. As a result, it may be possible to provide the passive MEMS switch circuit in a low power apparatus for supporting such applications as the Internet-of-Things (IoT).

Abstract: An envelope tracking (ET) radio frequency (RF) front-end circuit is provided. The ET RF front-end circuit includes an ET integrated circuit(s) (ETIC(s)), a local transceiver circuit, a target voltage circuit(s), and a number of power amplifiers. The local transceiver circuit receives an input signal(s) from a coupled baseband transceiver and generates a number of RF signals. The target voltage circuit(s) generates a time-variant ET target voltage(s) based on the input signal(s). The ETIC(s) generates multiple ET voltages based on the time-variant ET target voltage(s). The power amplifiers amplify the RF signals based on the ET voltages. Given that the time-variant ET target voltage(s) is generated inside the self-contained ET RF front-end circuit, it is possible to reduce distortion in the time-variant ET target voltage(s), thus helping to improve operating efficiency of the power amplifiers, especially when the RF signals are modulated with a higher modulation bandwidth (e.g., ?200 MHz).

Abstract: An envelope tracking (ET) power amplifier apparatus with predistortion includes an amplifier circuit configured to amplify a radio frequency (RF) signal based on an ET voltage and a tracker circuit configured to generate the ET voltage based on an ET target voltage. The amplifier circuit may introduce phase and amplitude distortions to the signal being amplified. To offset such distortions, exemplary aspects of the present disclosure add an isogain predistortion circuit in an ET integrated circuit (IC) to correct for amplitude distortions and add a phase modulation predistortion circuit to correct for phase distortions.

Abstract: An apparatus and method for calibrating an envelope tracking (ET) lookup table (LUT) are provided. An ET power management apparatus includes a power amplifier configured to amplify a radio frequency (RF) signal from a time-variant input power to a time-variant output power linearly related to the time-variant input power. A calibration circuit is employed to receive a time-variant output power feedback nonlinearly related to the time-variant input power, determine a linear relationship between the time-variant input power and the time-variant output power based on the time-variant output power feedback, and calibrate the ET LUT based on the determined linear relationship. As a result, it is possible to improve accuracy of the ET LUT to thereby improve operating efficiency and linearity of the power amplifier.