Power amplifier

Abstract

In a power amplifier for amplifying power using a transistor, the transistor includes a plurality of transistor units connected in parallel and having different static characteristics or pinch-off voltages. When a bias voltage applied to the plurality of transistor units is lowered, predetermined transistor units of the plurality of transistor units are turned off by pinch-off, and the remaining transistor units are in an ON state.

Description

technical field [0001] The present invention relates to a power amplifier, and more particularly, to an amplifier in which transistors having a new structure are used to achieve downsizing without lowering efficiency in low output modes. Background technique [0002] Generally, when a radio frequency device transmits a radio frequency signal, the transmitted signal is amplified by a power amplifier and output with a set power. For such power amplifiers, lower power consumption and higher efficiency are required. [0003] As a commonly used amplifier with low power consumption, Japanese Unexamined Patent Publication No. 1-117405 discloses an operational amplifier, Japanese Unexamined Patent Publication No. 5-243862 discloses a field effect transistor amplifier circuit, and Japanese Unexamined Patent Publication No. No. 7-202595 discloses an inverting amplifier. [0004] Generally, when using such commonly used power amplifiers and continuously changing their output, the mag...

AI Technical Summary

Problems solved by technology

[0007] Therefore, devices using such power amplifiers become overly large

It is disadvantageous to use such a power amplifier in, for example, a portable telephone where space is limited and size reduction is required

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