Variable inductor, oscillator including the variable inductor and radio terminal comprising this oscillator, and amplifier including the variable inductor and radio terminal comprising this amplifier

摘要

An amplifier comprises an amplifier circuit which comprises a first inductor as an impedance element for degeneration, and a control circuit which has a second inductor electro-magnetically connected to the first inductor, and changes a control current flowing through the second inductor to change an inductance value of the first inductor, thereby changing amplification characteristics of the amplifier circuit.