Electronic circuit and electronic device

1. An electronic circuit comprising:

a first inductor;

multiple second inductors that are magnetically coupled with the first inductor, induced current flowing through the multiple second inductors by a magnetic field generated by the first inductor; and

a current changing part that is connected to the multiple second inductors and is configured to change the induced current that flows through the multiple second inductors inductor,

wherein the multiple second inductors are formed inside the first inductor and have different inner diameters,

wherein the current changing part includes a switching part that switches the induced current flowing through each of the multiple second inductors to zero or a predetermined value other than zero so that inductance of the first inductor changes stepwise.

2. The electronic circuit as claimed in claim 1 , wherein the switching part includes a switch that is connected between ends of the second inductor and opens or closes the second inductor.

3. The electronic circuit as claimed in claim 1 , further comprising an adjusting part that continuously changes the induced current flowing through the second inductor within a given range.

4. The electronic circuit as claimed in claim 3 , wherein the adjusting part includes an additional impedance that is connected to an end of the second inductor and continuously changes the impedance of the second inductor.

5. The electronic circuit as claimed in claim 4 , wherein the additional impedance includes a variable capacitance diode.

6. The electronic circuit as claimed in claim 1 , wherein the first inductor and the multiple second inductors include wiring patterns formed on a substrate.

7. The electronic circuit as claimed in claim 6 , wherein the first inductor and the multiple second inductors are formed on an identical layer on the substrate.

8. The electronic circuit as claimed in claim 6 , wherein the first inductor and the multiple second inductors are formed on different layers that are stacked so as to include an interposed insulating layer between the different layers.

9. The electronic circuit as claimed in claim 8 , wherein the multiple second inductors are formed on different layers and include portions that overlap each other in a direction in which the different layers are stacked.

10. The electronic circuit as claimed in claim 1 , further comprising an amplifier part that amplifiers an input signal, a matching circuit that includes the first inductor and matches an output impedance of the amplifier part, and a control part that controls the current changing part on the basis of the input signal and changes an impedance of the matching circuit.

11. The electronic circuit as claimed in claim 10 , wherein the control circuit changes the impedance of the matching circuit so that a power added efficiency increases as the input signal decreases and a saturated power of the electronic circuit increases as the input signal increases.

12. The electronic circuit as claimed in claim 10 , wherein the current changing part includes a variable capacitance diode connected to an end of the second inductor, and the control circuit changes the impedance of the matching circuit so that the saturated power of the electronic circuit increases as the input signal increases.

13. The electronic circuit as claimed in claim 1 , comprising a low-pass filter circuit, and wherein the first inductor is included in the low-pass filter circuit.

14. The electronic circuit as claimed in claim 13 , wherein the first inductor is connected in series between an input terminal of the low pass filter circuit and an output terminal thereof.

15. The electronic circuit as claimed in claim 1 , further comprising a high-pass filter circuit including the first inductor.

16. An electronic device comprising the electronic circuit as claimed in claim 1 .