Abstract: The present invention provides a technology capable of achieving an improvement in the characteristic of a power amplifier when a power amplifier mounted onto mobile communication equipment such as a cellular phone is comprised of the balance amplifier. One feature of an embodiment resides in that each of passive parts disposed in a low-band signal negative path and each of passive parts disposed in a low-band signal positive path are placed in positions where they are symmetric with respect to a center line of a semiconductor chip. Thus, the symmetry between the low-band signal negative path and the low-band signal positive path is enhanced. As a result, a loss in matching due to the difference between the low-band signal negative path and the low-band signal positive path can be enough reduced, and the characteristic of a low-band signal balance amplifier can be enhanced.

Abstract: The present invention provides a technology capable of achieving an improvement in the characteristic of a power amplifier when a power amplifier mounted onto mobile communication equipment such as a cellular phone is comprised of the balance amplifier. One feature of an embodiment resides in that each of passive parts disposed in a low-band signal negative path and each of passive parts disposed in a low-band signal positive path are placed in positions where they are symmetric with respect to a center line of a semiconductor chip. Thus, the symmetry between the low-band signal negative path and the low-band signal positive path is enhanced. As a result, a loss in matching due to the difference between the low-band signal negative path and the low-band signal positive path can be enough reduced, and the characteristic of a low-band signal balance amplifier can be enhanced.

Abstract: An electronic part for a high frequency power amplifier is provided which is designed to constitute at least a part of a wireless communication system for performing feedback control by detecting an output power, and which can miniaturize a directional coupler. Also, the electronic part permits control of the output power with high accuracy without having any influence on a monitor voltage by a reflected wave propagating through a line of the directional coupler. The directional coupler includes a subline disposed in parallel to and in the vicinity of a part of a main line of an impedance matching circuit on the last output stage side of a power amplifier circuit, a capacitance element connected to between the main line and the subline, and a resistor element connected to between a constant potential point and a termination side of the subline.