Analog switch circuit for wide frequency band

1. An analog switch circuit comprising:

a first field-effect transistor, a source of which is coupled to a first switch terminal, and a drain of which is coupled to a second switch terminal;

a first capacitance to store electric charge;

a second capacitance to store electric charge;

a first switching element that is coupled between the direct current voltage node and a first terminal of the first capacitance;

a second switching element that is coupled between the reference potential node and a second terminal of the first capacitance;

a third switching element that is coupled between the first terminal of the first capacitance and a first terminal of the second capacitance;

a fourth switching element that is coupled between the second terminal of the first capacitance and a second terminal of the second capacitance;

a fifth switching element that is coupled between the first terminal of the second capacitance and a gate of the first field-effect transistor; and

a sixth switching element that is coupled between the second terminal of the second capacitance and the source of the first field-effect transistor.

2. The analog switch circuit according to claim 1 , further comprising:

a second field-effect transistor with a polarity opposite to the first field-effect transistor, a source of the second field-effect transistor being coupled to the first switch terminal and a drain of the second field-effect transistor being coupled to the second switch terminal;

a third capacitance to store electric charge;

a fourth switch circuit that couples the first capacitance and the third capacitance in parallel; and

a fifth switch circuit that couples the third capacitance between a gate and the source of the second field-effect transistor.

3. The analog switch circuit according to claim 1 , further comprising:

a detection circuit that detects a voltage between the gate and the source of the first field-effect transistor and controls the first switch circuit and the second switch circuit based on the detected voltage between the gate and the source of the first field-effect transistor.

4. The analog switch circuit according to claim 1 , further comprising:

a second field-effect transistor, a source of the second field-effect transistor being coupled to a third switch terminal, and a drain of the second field-effect transistor being coupled to a fourth switch terminal;

a third capacitance to store electric charge;

a fourth switch circuit that couples the first capacitance and the third capacitance in parallel; and

a fifth switch circuit that couples the third capacitance between a gate and the source of the second field-effect transistor.

5. The analog switch circuit according to claim 1 , further comprising:

a variable direct current power supply that is coupled between the direct current voltage node and the reference potential node and supplies a variable direct current voltage.

6. The analog switch circuit according to claim 1 , further comprising:

a back gate switch circuit that couples a back gate of the first field-effect transistor to one of the source and the reference potential node.

7. The analog switch circuit according to claim 1 , further comprising:

a third capacitance to store electric charge;

a fourth switch circuit that couples the third capacitance between the direct current voltage node and the reference potential node; and

a fifth switch circuit that couples the second capacitance and the third capacitance in parallel.