Power amplifier circuit
A power amplifier circuit includes a first amplifier; a first transformer including a first primary coil connected to an output of the first amplifier and a first secondary coil electromagnetically coupled to the first primary coil; a second amplifier connected to one end of the first secondary coil; a third amplifier connected to another end of the first secondary coil; a second transformer including a second primary coil having one end connected to an output of the second amplifier and another end connected to an output of the third amplifier, and a second secondary coil electromagnetically coupled to the second primary coil; a first capacitance element provided between the second secondary coil and a ground; and a second capacitance element having one end connected to one end of the second secondary coil and another end connected to another end of the second secondary coil.
1. A power amplifier circuit comprising:
a first amplifier configured to amplify an input signal;
a first transformer including a first primary coil connected to an output of the first amplifier, and a first secondary coil coupled to the first primary coil via a first electromagnetic field;
a second amplifier connected to a first end of the first secondary coil;
a third amplifier connected to a second end of the first secondary coil;
a second transformer including a second primary coil having a first end connected to an output of the second amplifier, and a second end connected to an output of the third amplifier, and a second secondary coil coupled to the second primary coil via a second electromagnetic field;
a first capacitance element between the second secondary coil and a ground; and
a second capacitance element having a first end connected to a first end of the second secondary coil, and a second end connected to a second end of the second secondary coil,
wherein the second end of the second secondary coil is connected to a node between the first capacitance element and the second capacitance element.
2. The power amplifier circuit according to claim 1 , further comprising:
a third capacitance element between the first primary coil and ground; and
a fourth capacitance element having a first end connected to a first end of the first primary coil and a second end connected to a second end of the first primary coil.
3. The power amplifier circuit according to claim 1 , further comprising:
a third capacitance element between the first primary coil and ground.
4. The power amplifier circuit according to claim 1 , wherein, in the second transformer, the second primary coil and the second secondary coil comprise at least one line of a substrate in or on which the power amplifier circuit is located.
5. The power amplifier circuit according to claim 2 , wherein, in the second transformer, the second primary coil and the second secondary coil comprise at least one line of a substrate in or on which the power amplifier circuit is located.
6. The power amplifier circuit according to claim 1 , wherein the second capacitance element comprises a line of a substrate in or on which the power amplifier circuit is located.
7. The power amplifier circuit according to claim 2 , wherein the second capacitance element comprises a line of a substrate in or on which the power amplifier circuit is located.
8. The power amplifier circuit according to claim 4 , wherein the second capacitance element comprises a line of a substrate in or on which the power amplifier circuit is located.
9. The power amplifier circuit according to claim 1 , wherein the first amplifier comprises a plurality of amplifiers coupled in series.
10. The power amplifier circuit according to claim 2 , wherein the first amplifier comprises a plurality of amplifiers coupled in series.
11. The power amplifier circuit according to claim 4 , wherein the first amplifier comprises a plurality of amplifiers coupled in series.
12. The power amplifier circuit according to claim 6 , wherein the first amplifier comprises a plurality of amplifiers coupled in series.