There are provided an electronic component for high frequency power amplification provided with a high-sensitivity output power detection circuit which is immune to the influence of changes in the use environment thereof, free of an output mismatch, small in size, and low in insertion loss and a wireless communication system using the electronic component. There are provided an output detection transistor which receives, at a control terminal, a voltage extracted from the intermediate node of an impedance matching circuit provided between the final-stage power amplification transistor of a high-frequency power amplification circuit and an output terminal thereof via a capacitor element and allows a current proportional to an output power to flow, a bias generation circuit for giving an operating point to the control terminal of the transistor, a current mirror circuit for transferring the current flowing in the output detection transistor, and a current-to-voltage conversion transistor for converting the transferred current to a voltage.
In radio communication system that is able to transmit in two or more modulation modes, e.g., one modulation mode when phase shifts are performed and another modulation mode when phase shifts and amplitude shifts are performed, the disclosed invention can avoid that receiving band noise becomes so great not to conform to the GSM standards' prescription for such noise in a high voltage region of the power supply voltage, even when the output power is controlled by changing the amplitude of the input signal to the power amplifier circuitry while fixing the bias voltages to be applied to the power amplifying transistors. When the output power is controlled as above, in the modulation mode (GSM mode) when phase shifts are performed, idle currents flowing across the power amplifying transistors are regulated, depending on the power supply voltage, i.e., the idle currents are decreased when the power supply voltage is high and increased when the power supply voltage is low.
