A device includes a substrate and a package input terminal. The device includes a driver amplifier mounted to the substrate and configured to receive a radio frequency input signal. A first amplifier is mounted to the substrate. The first amplifier includes a first amplifier input terminal. A second amplifier is mounted to the substrate. The second amplifier includes a second amplifier input terminal. An inter-stage network is connected between the driver amplifier and the first amplifier and between the driver amplifier and the second amplifier. The inter-stage network includes a first capacitor connected between the driver amplifier and the first amplifier input terminal, and an inductor having a first terminal and a second terminal. The first terminal of the inductor is connected to the first capacitor. The inter-stage network includes a second capacitor connected between the second terminal of the inductor and the second amplifier input terminal.

Wideband power combiners and splitters are provided herein. In certain embodiments, a power combiner/splitter is implemented with a first coil connecting a first port and a second port, and a second coil connecting a third port and a fourth port. The first coil and the second coil are inductively coupled to one another. For example, the first coil and the second coil can be formed using adjacent conductive layers of a semiconductor chip, an integrated passive device, or a laminate. The power combiner/splitter further includes a fifth port tapping a center of the first coil and a sixth port tapping a center of the second coil. The fifth port and the sixth port serve to connect capacitors and/or other impedance to the center of the coils to thereby provide wideband operation.

Methods and apparatus for providing high efficiency power amplifiers for both high and low output power levels are disclosed. An example apparatus includes a first amplifier to amplify a signal from a host device; and transmit the amplified signal to an antenna; a second amplifier to amplify the signal from the host device; and transmit the amplified signal to the antenna; and first, second, and third switches to: when the first and second switches are closed and the third switch is open, couple the first amplifier to the second amplifier in a parallel structure; and when the first and second switches are open and the third switch is closed, couple the first amplifier to the second amplifier in a stacked structure.

A Doherty amplifier has a first amplifier path that includes a first amplifier, a second amplifier path that includes a second amplifier, a power divider, and a short-circuited stub. The power divider receives an RF signal and divides the RF signal into first and second input signals. The power divider includes first and second power divider outputs that produce the first and second input signals, respectively. The short-circuited stub is coupled between the first power divider output and the first amplifier or between the second power divider output and the second amplifier. The first and second amplifier paths are characterized by first and second frequency-dependent insertion phases, respectively. A slope of the first or second frequency-dependent insertion phase is altered by the short-circuited stub. The power divider produces the first and second input signals with a quadrature phase shift.

A balanced amplifier system having input and output quadrature couplers or equivalents thereof and two amplifiers there between. An RF signal is presented to a first input of an input quadrature coupler such that an amplified RF signal is output at a first output of the output quadrature coupler. A RF control signal is presented to a second input of the quadrature coupler such that an amplified control signal is outputted at the other output of the output quadrature coupler. The system is configured to reflect the amplified signal back into the second port of the output quadrature coupler in order to vary an impedance seen by the amplifiers of the balanced amplifier.

A power amplifier module includes a module substrate. First and second heat dissipation structures extend through the module substrate, and each has a first surface exposed at a mounting surface of the module substrate, and a second surface exposed at a bottom surface of the module substrate. The first surfaces of the first and second heat dissipation structures are physically separated by a portion of the mounting surface. First and second amplifier dies are coupled to the first surface of the first heat dissipation structure. The first amplifier die includes a first power transistor that functions as a driver amplifier. The second amplifier die includes a second power transistor that functions as a first final amplifier. The third amplifier die is coupled to the first surface of the second heat dissipation structure, and the third amplifier die includes a third power transistor that functions as a second final amplifier.

A distributed active transformer includes an input transformer set and an output transformer set. Active stages are coupled between a transformer in the input transformer set and a transformer in the output transformer set. The input and output transformer sets are each configured as a slab transformer. The input slab transformer includes a single primary slab and many secondary slabs. The output slab transformer includes many primary slabs and a single secondary slab.

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.

A power amplifier includes: plural amplifiers; a tournament-tree-shaped circuit connected with the plural amplifiers and including plural transmission lines arranged in a tournament-tree shape; and plural difference frequency short circuits shunt-connected with plural nodes of the tournament-tree-shaped circuit, wherein each of the plural difference frequency short circuits includes an inductor and a capacitor connected in series, resonant frequencies of the plural difference frequency short circuits become lower as the plural difference frequency short circuits are more separated from the plural amplifiers, and the difference frequency short circuits having equivalent resonant frequencies are connected with plural nodes in the same stage among the plural nodes.

Disclosed is a reconfigurable power amplifier having a 2.sup.N?1 number of input-side reconfigurable quadrature couplers connected in a tree structure, wherein a 2.sup.(N?1) number of the input-side reconfigurable quadrature couplers have coupler output terminals, and a root of the tree structure is one of the input-side reconfigurable quadrature couplers having a main input terminal. Also included is a 2.sup.N?1 number of output-side reconfigurable quadrature couplers connected in a tree structure, wherein a 2.sup.(N?1) number of the output-side reconfigurable quadrature couplers have coupler input terminals, and a root of the tree structure is one of the output-side reconfigurable quadrature couplers having a main output terminal. Further included is a 2.sup.N number of constituent amplifiers divided into amplifier pairs having amplifier input terminals connected to corresponding ones of the coupler output terminals and having amplifier output terminals coupled to corresponding ones of the coupler input terminals.