Industrial Technology Research Institute

Chih-Chun Shen

Shih-Ming Wang

Wei-Tsung Li

Yu-Cheng Liu

A linearity improving system and a linearity improving method are provided. The linearity improving system includes a coupler, a downconverter and a transformer. The coupler is configured to couple a part of an input RF signal. The downconverter coupled to the coupler converts the input RF signal to a fundamental frequency and outputs a modulation signal. The transformer coupled to the downconverter adjusts a phase and a power of the modulation signal. After the input RF signal and the modulation signal being adjusted are inputted to an amplifier, the amplifier outputs an output RF signal.

Linearity improving system and linearity improving method

A power amplifier circuit including a power transistor, a variable impedance circuit, first and second envelope detecting circuits is provided. The power transistor receives an input signal and outputs an output signal. The variable impedance circuit includes an impedance control transistor and a first filter capacitor. An equivalent impedance of the variable impedance circuit varies with the input signal. The impedance control transistor is coupled to the power transistor and receives a control voltage. The first filter capacitor is coupled between the impedance control transistor and ground. Both the first and the second envelope detecting circuits detect the input signal to dynamically control the equivalent impedance of the variable impedance circuit.

Growing community of inventors

Kaohsiung, Taiwan

Chih-Chun Shen