The present disclosure provides an audio amplifying circuit and a playing device, including: N-order filters and an integrated circuit; after an original audio signal passes through the N-order filters, a filtered signal is obtained; after the filtered signal passes through the integrated circuit, a corresponding digital signal is output; where the number of operational amplifiers adopted in the N-order filters is smaller than N, and N is a natural number greater than 1.

Leadless power amplifier (PA) packages having topside termination interposer (TTI) arrangements, and associated fabrication methods, are disclosed. Embodiments of the leadless PA package include a base flange, a first set of interposer mount pads, a first RF power die, a package body. The first RF power die is attached to a die mount surface of the base flange and electrically interconnected with the first set of interposer mount pads. The TTI arrangement is electrically coupled to the first set of interposer mount pads and projects therefrom in the package height direction. The package body encloses the first RF power die and having a package topside surface opposite the lower flange surface. Topside input/output terminals of the PA package are accessible from the package topside surface and are electrically interconnected with the first RF power die through the TTI arrangement and the first set of interposer mount pads.

Leadless power amplifier (PA) packages having topside termination interposer (TTI) arrangements, and associated fabrication methods, are disclosed. Embodiments of the leadless PA package include a base flange, a first set of interposer mount pads, a first RF power die, a package body. The first RF power die is attached to a die mount surface of the base flange and electrically interconnected with the first set of interposer mount pads. The TTI arrangement is electrically coupled to the first set of interposer mount pads and projects therefrom in the package height direction. The package body encloses the first RF power die and having a package topside surface opposite the lower flange surface. Topside input/output terminals of the PA package are accessible from the package topside surface and are electrically interconnected with the first RF power die through the TTI arrangement and the first set of interposer mount pads.

An uplink multiple input-multiple output (MIMO) transmitter apparatus includes a transmitter chain that includes a sigma-delta circuit that creates a summed (sigma) signal and a difference (delta) signal from two original signals to be transmitted. These new sigma and delta signals are amplified by power amplifiers to a desired output level before having two signals reconstructed from the amplified sigma and amplified delta signals by a second circuit. These reconstructed signals match the two original signals in content but are at a desired amplified level relative to the two original signals. The reconstructed signals are then transmitted through respective antennas as uplink signals. By employing this uplink MIMO transmitter apparatus, it is possible to use smaller power amplifiers, which may reduce footprint, power consumption, and costs of the uplink MIMO transmitter apparatus.

An uplink multiple input-multiple output (MIMO) transmitter apparatus includes a transmitter chain that includes a sigma-delta circuit that creates a summed (sigma) signal and a difference (delta) signal from two original signals to be transmitted. These new sigma and delta signals are amplified by power amplifiers to a desired output level before having two signals reconstructed from the amplified sigma and amplified delta signals by a second circuit. These reconstructed signals match the two original signals in content but are at a desired amplified level relative to the two original signals. The reconstructed signals are then transmitted through respective antennas as uplink signals. By employing this uplink MIMO transmitter apparatus, it is possible to use smaller power amplifiers, which may reduce footprint, power consumption, and costs of the uplink MIMO transmitter apparatus.

Example embodiments relate to power amplifiers and Doherty amplifiers that include the same. One example embodiment includes a power amplifier. The power amplifier includes one or more radiofrequency (RF) output terminals. The power amplifier also includes a Gallium Nitride (GaN) semiconductor die on which a power field-effect transistor (FET) is integrated. The FET includes a plurality of FET cells that are adjacently arranged in a row. The FET cells are connected either directly or indirectly to the one or more RF output terminals via a respective first inductor. For FET cells arranged at opposing ends of the row of FET cells, a total FET cell gate width and an inductance of the first inductor is larger and smaller than the total FET cell gate width and inductance of the first inductor for one or more FET cells arranged in the middle of the row of FET cells, respectively.

A method includes receiving first data associated with a first power amplifier and second data associated with a second power amplifier. The method also includes generating a first amplitude limiting signal having gain parameters that are based on the first data and the second data. The first data includes at least one of a temperature measurement associated with the first power amplifier, a supply voltage measurement associated with the first power amplifier, a load resistance associated with the first power amplifier, or a gain associated with the first power amplifier. The method further includes modifying an audio signal based at least in part on the first amplitude limiting signal to generate a first gain-adjusted audio signal. The method also includes providing a first output audio signal to the first power amplifier for amplification. The first output audio signal is based at least in part on the first gain-adjusted audio signal.

A circuit element is formed on a substrate made of a compound semiconductor. A bonding pad is disposed on the circuit element so as to at least partially overlap the circuit element. The bonding pad includes a first metal film and a second metal film formed on the first metal film. A metal material of the second metal film has a higher Young's modulus than a metal material of the first metal film.

A circuit element is formed on a substrate made of a compound semiconductor. A bonding pad is disposed on the circuit element so as to at least partially overlap the circuit element. The bonding pad includes a first metal film and a second metal film formed on the first metal film. A metal material of the second metal film has a higher Young's modulus than a metal material of the first metal film.

Circuitry for driving a load, the circuitry comprising: driver circuitry; and load sensing circuitry, wherein the circuitry is operable in: a driving mode of operation in which the driver circuitry supplies a drive signal to a load coupled to the circuitry; and a load sensing mode of operation, for estimating a characteristic of a load coupled to the circuitry based on a signal output by the load sensing circuitry in response to a stimulus signal, wherein the circuitry is configured to, in response to a request for operation of the circuitry in the load sensing mode: compare an indication of a current through the load to a predefined threshold; and if the indication of the current through the load meets the predefined threshold, prevent or delay operation in the load sensing mode.