An amplifier includes amplifier circuits connected in series between a ground and a power supply, each amplifier circuit includes: a transistor; and a first capacitance, one end of which is connected to a drain of the transistor, a first amplifier circuit connected closest to the power supply includes a load connected between the drain of the transistor and the power supply, each of the amplifier circuits except for the first amplifier circuit includes a load connected between the drain of the transistor of an own amplifier circuit and a source of the transistor of an amplifier circuit adjacent to the own amplifier circuit, each of the amplifier circuits except for an amplifier circuit connected farthest from the power supply includes a second capacitance connected between the source of the transistor and the ground, and the second capacitance has a capacitance value larger than a capacitance value of the first capacitance.

Systems, methods, and devices relate to tunable baluns for multimode power amplification. For example, a variable-gain amplification system can include a power amplifier configured to provide an amplified signal and to selectively operate in at least a first gain mode and a second gain mode. The variable-gain amplification system can also include a tunable balun circuit configured to receive the amplified signal from the power amplifier and to provide an output signal. The tunable balun circuit can be configured to implement a first turn ratio for the first gain mode and a second turn ratio for the second gain mode.

A balun configured for a power range between 500 W and 5 kW output includes a balanced signal port comprising a first connection and a second connection and further includes a single-ended signal port comprising a third connection and a fourth connection, the fourth connection being connected to ground. In addition, the balun includes a first capacitor disposed between the first connection and a first end of a first resistor and a second capacitor disposed between the second connection and the first end of the first resistor. A second end of the first resistor is connected to ground.

A circuit (200) for testing failure of a connection between a radio frequency, RF, integrated circuit (201) and external circuitry (204), the circuit comprising: an amplifier (205) having first and second input paths (215, 216) and first and second output paths (206, 207); a first power detector (208, 209) coupled to one of said first or second output paths; at least one connection (211) between said first and second output paths (206, 207) and said external circuitry (204), connecting said outputs to a RF combiner (210) said external circuitry; at least one disabling circuit (230, 232, 234, 236, 240, 242, 260, 262) coupled to at least one of said first and second output paths (206, 207) or at least one of said first and second input path (215, 216), before said path reaches said power detector (208, 209); for disabling one of said inputs or outputs; wherein when said input or output path is disabled (206, 207), and a signal is output along the enabled output path (206, 207), the power detector (208, 209) on said disabled output path can detect if there is a failure in said at least one connection (211).

A Radio Frequency (RF) circuit including a receive path, a transmit path, a switching circuit, and an output configured to receive RF signals from an antenna in a receive mode of operation, and to provide RF signals to the antenna in a transmit mode of operation. The receive path is configured to be coupled between a low-noise amplifier and the output. The switching circuit is located in the receive path and is configured, in the receive mode, to selectively couple the low-noise amplifier to the output and to pass the received RF signals from the output to the low-noise amplifier. The transmit path is configured to be coupled between a power amplifier and the output, to provide, in the transmit mode, signals from the power amplifier to the output, bypassing the switching circuit, and to have, in receive mode of operation, an off-state impedance of at least 200+j*13 Ohm.

A balun is disclosed and includes a dielectric substrate defining a first surface and a second surface. The balun includes a first output port including a first output ground portion and first output power portion; a second output port including a second output ground portion and a second output power portion; and an input port including an input ground portion and input power portion. The first output ground portion, the second output ground portion, and the input ground portion are coupled at a ground junction portion. The first output power portion, the second output power portion, and the input power portion are coupled at a power junction portion. The first output power portion, the second output power portion, and the input power portion are positioned on the first surface. The first output ground portion, the second output ground portion, and the input ground portion are positioned on the second surface.

Techniques for monitoring a distortion signal of a power amplifier circuit, where the output of a distortion monitoring circuit includes little or no fundamental signal and closely represents the actual distortion of the amplifier circuit of a wired communications system. The power amplifier circuit can generate a distortion feedback signal that does not affect the power amplifier's output power capability, e.g., no inherent loss in the fundamental output of the amplifier. That is, using a distortion monitor circuit, the power amplifier circuit can resolve a distortion feedback signal from the intended output signal of the output power amplifier circuit.

Embodiments of a device and method are disclosed. In an embodiment, an RF amplifier includes first and second RF signal paths having RF input interfaces, RF output interfaces, and corresponding transistors connected between the respective RF input interfaces and RF output interfaces, wherein control terminals of the transistors are connected to the RF input interfaces and current conducting terminals of the transistors are connected to the corresponding RF output interfaces. The RF amplifier including a conductive path between the current conducting terminal of the first transistor and the current conducting terminal of the second transistor, wherein the conductive path includes a first inductance, a second inductance, and a capacitance electrically connected between the first inductance and the second inductance.

An amplifier circuit includes an amplifier, a balun comprising a primary side having a primary inductance and a secondary side having a secondary inductance, the primary side coupled to an output of the amplifier, the secondary side coupled to a first output path of the amplifier circuit and a second output path of the amplifier circuit, a shunt inductance coupled to the first output path; and a compensating inductance in the balun, the compensating inductance coupled between a first node and a second node, the first node coupling the compensating inductance to the first output path, the second node coupling the secondary inductance to the compensating inductance.

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode, and a low noise amplifier (LNA) that converts a differential input to a single-ended output with respect to ground. The first interdigital transducer electrode may be single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The LNA may have a differential input connected to the acoustic wave filter, a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter, and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.