Abstract: Power amplifier (PA) packages having air cavities enclosed by electrically-routed lids, as well as to method for fabricating such power amplifier packages, are disclosed. In embodiments, the PA package includes a package body having a package topside surface and a package bottomside surface. The package body is defined, at least in part, by a package substrate and an electrically-routed lid bonded to the package substrate to sealingly enclose an air cavity. The electrically-routed lid includes, in turn, an upper lid wall, peripheral lid sidewalls, and sidewall-embedded vias contained in the peripheral lid sidewalls and each extending essentially in a package height direction. Radio frequency (RF) circuitry is attached to the package substrate and located within the air cavity, while a topside input/output interface is provided on the upper lid wall and electrically interconnected with the RF circuitry through the sidewall-embedded vias of the electrically-routed lid.

Abstract: A system includes a reference field effect transistor (FET), wherein the reference FET is a depletion mode transistor, and a bias control circuit. The bias control circuit includes a voltage sensor connected to a drain terminal of the reference FET. The voltage sensor is configured to measure a voltage at the drain terminal of the reference FET as a measured voltage, determine a voltage difference between a reference voltage and the measured voltage, and output the voltage difference at a voltage sensor output terminal. The system includes a translation circuit connected the voltage sensor output terminal. The translation circuit is configured to convert the voltage difference into a negative gate bias voltage, and apply the negative gate bias voltage to a gate terminal of the reference FET.

Abstract: An amplifier system includes an amplifier transistor and a reference transistor used to provide a direct current (DC) bias voltage to bias a gate terminal of the amplifier transistor. The amplifier transistor may have a drain terminal coupled to a drain voltage supply and a radio frequency (RF) output node and a gate terminal coupled to bias circuitry that includes the reference transistor. The reference transistor may have a gate terminal coupled to a reference potential, a drain terminal coupled to the drain voltage supply, and a source terminal coupled to a constant current source and to the gate terminal of the amplifier transistor. The reference transistor may be formed on the same die as the amplifier transistor and may have a threshold voltage that is correlated with that of the amplifier transistor.

Abstract: Embodiments of a device and method are disclosed. In an embodiment, a current sensing circuit includes first and second integrated resistors on a semiconductor die, a controllable current source configured to provide a reference current, and a current determination circuit. A resistance value of the second integrated resistor is a factor n larger than a resistance value of the first integrated resistor. A current drawn by a target circuit is configured to flow through the first integrated resistor, and the reference current is configured to flow through the second integrated resistor. The current determination circuit is configured to determine a value of the current drawn by the target circuit based on the value of the reference current when a first voltage at a terminal of the first integrated resistor is approximately equal to a second voltage at a terminal of the second integrated resistor.

Abstract: A device includes a package body including a central flange and an amplifier module mounted to the central flange of the surface-mount device. The amplifier module includes a module substrate mounted to the central flange. The module substrate includes a first die mount window, a first circuitry on a first surface of the module substrate, a second circuitry on the first surface of the module substrate, and a first amplifier die mounted on the central flange. The first amplifier die is at least partially disposed within the first die mount window and the first amplifier die is electrically connected to the first circuitry and the second circuitry. The first circuitry is electrically connected to a first lead of the package body and the second circuitry is electrically connected to a second lead of the package body.

Abstract: A musical instrument support apparatus for displaying a guitar in a plurality of viewing positions may include a securement frame configured to be rotatably mounted to a vertical surface and including a plurality of bars connected together; a pair of side arms pivotably mounted to the securement frame, each arm in the pair of side arms configured to pivotably adjust to contact the body of the guitar; and a wall mount bracket attached to the securement frame and configured to be attached to the vertical surface. The support apparatus may be designed to secure the guitar with the body disposed on the support plate and the pair of sides of the body secured within the pair of arms, wherein the securement frame is rotatably adjusted relative to the support base to display the secured guitar in one of the plurality of viewing positions.

Abstract: A device includes an integrated circuit (IC) die. The IC die includes a silicon germanium (SiGe) substrate, a first RF signal input terminal, a first RF signal output terminal, a first amplification path between the first RF signal input terminal and the first RF signal output terminal, a second RF signal input terminal, a second RF signal output terminal, and a second amplification path between the second RF signal input terminal and the second RF signal output terminal. The device includes a first power transistor die including a first input terminal electrically connected to the first RF signal output terminal and a second power transistor die including a second input terminal electrically connected to the second RF signal output terminal. The first amplification path can include two heterojunction bipolar transistors (HBTs) connected in a cascode configuration and the second amplification path can include two HBTs connected in a cascode configuration.

Abstract: Embodiments of a device and method are disclosed. In an embodiment, a calibration circuit for a temperature sensor circuit includes a current source configured to generate a temperature independent reference current and further includes a voltage window generator circuit. The voltage window generator circuit is configured to generate a voltage window for the temperature sensor circuit using at least the temperature independent reference current. The voltage window is defined by a first reference voltage and a second reference voltage. The voltage window generator circuit is further configured to control a width of the voltage window to include a range of proportional to absolute temperature (PTAT) voltage outputs of a temperature sensor in the temperature sensor circuit.

Abstract: Doherty power amplifiers and devices are described with a low voltage driver stage in a carrier-path and a high voltage driver stage in a peaking-path. In an embodiment a Doherty power amplifier has a carrier-path driver stage transistor configured to operate using a first bias voltage at the driver stage output, and a final stage transistor configured to operate using a second bias voltage at the final stage output. A peaking-path driver stage transistor is configured to operate using a third bias voltage at the driver stage output, and a final stage transistor electrically coupled to the driver stage output of the peaking-path driver stage transistor is configured to operate using a fourth bias voltage at the final stage output, wherein the third bias voltage is at least twice as large as the first bias voltage.

Abstract: A power splitter for use in an amplifier (e.g., a Doherty amplifier) includes an input terminal, and first and second output terminals. The input terminal is configured to receive an input RF signal, the first output terminal is configured to produce a first RF output signal, and the second output terminal is configured to produce a second RF output signal. The power splitter also includes a first capacitance electrically coupled between the input terminal and the first output terminal, a second capacitance electrically coupled between the input terminal and the second output terminal, a first inductance electrically coupled between the input terminal and a ground reference node, a second inductance electrically coupled between the first output terminal and the ground reference node, a third inductance electrically coupled between the second output terminal and the ground reference node, and a resistance electrically coupled between the first and second output terminals.

Abstract: Embodiments of a device and method are disclosed. In an embodiment, a current sensing circuit includes first and second integrated resistors on a semiconductor die, a controllable current source configured to provide a reference current, and a current determination circuit. A resistance value of the second integrated resistor is a factor n larger than a resistance value of the first integrated resistor. A current drawn by a target circuit is configured to flow through the first integrated resistor, and the reference current is configured to flow through the second integrated resistor. The current determination circuit is configured to determine a value of the current drawn by the target circuit based on the value of the reference current when a first voltage at a terminal of the first integrated resistor is approximately equal to a second voltage at a terminal of the second integrated resistor.

Abstract: Doherty power amplifiers and devices are described with a low voltage driver stage in a carrier-path and a high voltage driver stage in a peaking-path. In an embodiment a Doherty power amplifier has a carrier-path driver stage transistor configured to operate using a first bias voltage at the driver stage output, and a final stage transistor configured to operate using a second bias voltage at the final stage output. A peaking-path driver stage transistor is configured to operate using a third bias voltage at the driver stage output, and a final stage transistor electrically coupled to the driver stage output of the peaking-path driver stage transistor is configured to operate using a fourth bias voltage at the final stage output, wherein the third bias voltage is at least twice as large as the first bias voltage.

Abstract: A musical instrument stand support apparatus with enhanced stability and a rotatable adjustment mechanism designed to display a guitar in one of a plurality of viewing positions is provided. The stand support apparatus includes a support base, a securement frame rotatably mounted to the support base and having a plurality of bars and a support plate, an upper cradle coupled to the securement frame, and a pair of arms pivotably mounted to the securement frame. The stand support apparatus is designed to secure the guitar with its body disposed on the support plate, guitar neck disposed within the upper cradle and pair of sides of the guitar body secured within the pair of arms. The securement frame is rotatably adjusted relative to the support base to display the secured guitar in one of the plurality of viewing positions.

Abstract: Embodiments of a method and a device are disclosed. In an embodiment, a method for operating a bias controller for an amplifier circuit involves obtaining temperature data corresponding to a temperature of the amplifier circuit, generating a proportional to absolute temperature (PTAT) bias voltage based on a first PTAT slope when the temperature is within a first range of temperatures or a second PTAT slope when the temperature is within a second range of temperatures, wherein the second PTAT slope is greater than the first PTAT slope, and biasing the amplifier circuit based on the generated PTAT bias voltage.

Abstract: Power amplifier modules (PAMs) having topside cooling interfaces are disclosed, as are methods for fabricating such PAMs. In embodiments, the method includes attaching the RF power die to a die support-surface of a module substrate. The RF power die is attached to the module substrate in an inverted orientation such that a frontside of the RF power die faces the module substrate. When attaching the RF power die to the module substrate, a frontside input/output interface of the RF power die is electrically coupled to corresponding substrate interconnect features of the module substrate. The method further includes providing a primary heat extraction path extending from the transistor channel of the RF power die to a topside cooling interface of the PAM in a direction opposite the module substrate.

Abstract: A power amplifier module includes a module substrate, a power transistor die, and a heat spreader. The module substrate has first, second, and third module pads exposed at a mounting surface. The power transistor die has an input/output surface that faces the mounting surface, an opposed ground surface, an input pad electrically coupled to the first module pad, an output pad electrically coupled to the second module pad, and an integrated power transistor. In an embodiment, the power transistor is a field effect transistor with a gate terminal coupled to the input pad, a drain terminal coupled to the output pad, and a source terminal coupled to the ground surface. The heat spreader has a thermal contact surface that is physically and electrically coupled to the ground surface of the power transistor die. An electrical ground contact structure is connected between the thermal contact surface and the third module pad.

Abstract: An embodiment of a Doherty amplifier includes a module substrate, first and second surface-mount devices coupled to a top surface of the module substrate, and an impedance inverter line assembly. The first and second surface-mount devices include first and second amplifier dies, respectively. The impedance inverter line assembly is electrically connected between outputs of the first and second amplifier dies. The impedance inverter line assembly includes an impedance inverter line coupled to the module substrate, a first lead of the first surface-mount device coupled between the first amplifier die output and a proximal end of the impedance inverter line, and a second lead of the second surface-mount device coupled between the second amplifier die output and a distal end of the impedance inverter line. According to a further embodiment, the impedance inverter line assembly has a 90 degree electrical length at a fundamental operational frequency of the Doherty amplifier.

Abstract: An amplifier includes a driver stage amplifier transistor and a final stage amplifier transistor, which are integrated in a semiconductor die. The driver stage amplifier transistor has a driver stage input, a driver stage output, and an output impedance, and the driver stage amplifier transistor is configured to operate using a first bias voltage at the driver stage output. The final stage amplifier transistor has a final stage input, a final stage output, and an input impedance. The final stage input is electrically coupled to the driver stage output. The final stage amplifier transistor is configured to operate using a second bias voltage at the final stage output, and the second bias voltage is at least twice as large as the first bias voltage.

Abstract: A Doherty amplifier module includes a substrate, an RF signal splitter, a carrier amplifier die, and first and second peaking amplifier dies. The RF signal splitter divides an input RF signal into first, second, and third input RF signals, and conveys the input RF signals to splitter output terminals. The carrier amplifier die includes one or more first power transistors configured to amplify, along a carrier signal path, the first input RF signal to produce an amplified first RF signal. The peaking amplifier dies each include one or more additional power transistors configured to amplify, along first and second peaking signal paths, the second and third input RF signals to produce amplified second and third RF signals. The dies are coupled to the substrate so that the RF signal paths through the carrier and one or more of the peaking amplifier dies extend in substantially different (e.g., orthogonal) directions.

Abstract: Embodiments of a method and a device are disclosed. In an embodiment, a Doherty amplifier module includes a substrate including a mounting surface, and further includes a first amplifier die, a second amplifier die, and a third amplifier die on the mounting surface. The first amplifier die is configured to amplify a first radio frequency (RF) signal along a first signal path, the second amplifier die is configured to amplify a second RF signal along a second signal path, and the third amplifier die is configured to amplify a third RF signal along a third signal path. A side of the first amplifier die including a first output terminal faces a side of the second amplifier die including a second output terminal. The second signal path is parallel to the first signal path, and the third signal path is orthogonal to the first and second signal paths.