Abstract:
A high frequency power amplifier maintains an excellent linearity regardless of a fluctuation of a load impedance and is downsized. The high frequency power amplifier detects an AC voltage amplitude at an output terminal of a final amplification stage transistor, and suppresses an input signal amplitude of a power amplifier when the voltage amplitude exceeds a predetermined threshold value.
Abstract:
The present invention provides a semiconductor device which comprises active components, passive components, wiring lines and electrodes and are satisfactory in terms of mechanical strength, miniaturization and thermal stability. In the semiconductor device, openings are formed just below active components. These openings are filled with conductor layers. Conductor layers are also formed where openings are not formed.
Abstract:
In a semiconductor device using an emitter top heterojunction bipolar transistor having a planar shape in a ring-like shape, a structure is provided in which a base electrode is present only on an inner side of a ring-like emitter-base junction region. This allows reduction of base/collector junction capacitance per unit emitter area, whereby a semiconductor device having high power adding efficiency and high power gain suitable for a power amplifier can be realized. Further, in a multistage power amplifier including first and second amplifier circuits each having one or more of bipolar transistors, a bipolar transistor in the first amplifier circuit uses an emitter having a planar shape in a rectangular shape, and a bipolar transistor in the second amplifier circuit uses an emitter having a ring-like shape and a base electrode only on the inner side of the emitter.
Abstract:
A power amplifier module comprises a plurality of amplifier stages, each including a reference amplifier for emulating the operation of the amplifier. The current flowing to the base of a bipolar transistor that forms each reference amplifier depending on an input power level is detected, amplified, and supplied as base current of the transistor of the corresponding amplifier.
Abstract:
A high frequency power amplifier maintains an excellent linearity regardless of a fluctuation of a load impedance and is downsized. The high frequency power amplifier detects an AC voltage amplitude at an output terminal of a final amplification stage transistor, and suppresses an input signal amplitude of a power amplifier when the voltage amplitude exceeds a predetermined threshold value.
Abstract:
For use in an amplifier configuration including a high-power amplifier and a low-power amplifier which are always interconnected in terms of high frequencies and between which switching is made using no switches, a highly stable high-frequency power amplifier module with high isolation between the amplifiers is provided. To reduce wrapping around from a low-power amplifier section in an activated state to a high-power amplifier section in a deactivated state or from the high-power amplifier section in an activated state to the low-power amplifier section in a deactivated state, an input matching circuit having high isolation characteristics is included in an input matching circuit portion which does not have much to do with amplifier efficiency. Switching of each of the amplifier sections between an activated state and a deactivated state is effected by control using bias input terminals.
Abstract:
In a base-bias-control-type high-frequency power amplifier with a plural stage configuration, a rising voltage of a base bias current supplied to an initial stage transistor is made lower than a rising voltage of a base bias current supplied to a second stage transistor by a bias circuit, and a difference between the both voltages is set to be smaller than a base-emitter voltage of an amplifying stage transistor. Also, a rising voltage of a base bias current supplied to a third stage transistor is made equal to the rising voltage of the base bias current supplied to an initial stage transistor. Accordingly, a technology capable of improving the power control linearity can be provided in a high-frequency power amplifier used in a polar-loop transmitter or the like.
Abstract:
An amplifier using a wide band, high efficiency, and low distortion amplifier free from clipping distortion, and a high efficiency and low distortion radio frequency power amplifier, using that amplifier, which can be applied to wide band wireless communication systems are provided. The amplifier has a DC—DC converter 2, augmented with a low pass filter 4, for amplifying the low frequency components of an input signal from a terminal 5, and a class B amplifier, augmented with a high pass filter, for amplifying the input signal and supplying its high frequency components after amplification. The DC—DC converter and the class B amplifier are connected in parallel, and the power supply voltage of the class B amplifier is controlled with the low frequency components of the input signal.
Abstract:
This invention is intended to provide an HBT capable of achieving, if the HBT is a collector-up HBT, the constriction of the emitter layer disposed directly under an external base layer, and reduction in base-emitter junction capacity, or if the HBT is an emitter-up HBT, reduction in base-collector junction capacity. For the collector-up HBT, window structures around the sidewalls of a collector are used to etch either the emitter layer disposed directly under the external base layer, or an emitter contact layer For the emitter-up HBT, window structures around the sidewalls of an emitter are used to etch either the collector layer disposed directly under the external base layer, or a collector contact layer. In both HBTs, the external base layer is supported by a columnar structure to ensure mechanical strength.
Abstract:
A CDMA system is provided which includes a power amplifier module have a DC current amplifier. The DC and current amplifier detects a DC component of an input signal and amplifies this detected DC component. The power amplifier module also includes an amplifier which receives the current amplified by the DC current amplifier as an input current. The input signal supplied to the DC current amplifier changes in response to an input power level.