| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a matching circuit, an amplification circuit and a communication device that implement a wide band gain of amplifiers.SOLUTION: The matching circuit provided for impedance matching between cascaded amplifiers each including an amplifying transistor includes a firstπtype bandpass filter connected between a first amplifier as a preceding stage amplifier and a second amplifier as a following stage amplifier. The firstπtype bandpass filter has: a first impedance element for loading an output of the first amplifier, and a ground capacitance for the amplifying transistor constituting the first amplifier; a second impedance element for a bias circuit corresponding to the amplifying transistor constituting the second amplifier, and a ground capacitance for the amplifying transistor constituting the second amplifier; and a capacitor for blocking a DC component of the output of the amplifying transistor constituting the first amplifier, and a third impedance element connected to the capacitor in series.</p> |
