Method of high voltage operation of a field effect transistor

1. A method of high voltage operation of a field effect transistor, comprising the steps of:

providing a field effect transistor that includes a substrate, a semiconductor channel formation region disposed in a surface of the substrate, a source region and a drain region which are spaced apart from each other with the semiconductor channel formation region disposed between the source region and the drain region, a gate insulating film region disposed on the semiconductor channel formation region, a resistive gate region disposed on the gate insulating film region, a source side electrode disposed on a source region side of the resistive gate region, and a drain side electrode disposed on a drain region side of the resistive gate region;

supplying a signal electric potential to the source side electrode of the field effect transistor; and

supplying to the drain side electrode of the field effect transistor, from a bias circuit, a bias electric potential an absolute value of which is equal to or larger than that of a specified electric potential and which changes according to an increase or decrease in a drain electric potential.

2. A method of high voltage operation of a field effect transistor according to claim 1 ; further comprising the step of supplying at least one of a signal electric potential and a signal current to the source region; and wherein the step of supplying the signal electric potential comprises supplying a first constant electric potential to the source side of the field effect transistor.

3. A method of high voltage operation of a field effect transistor according to claim 2 ; wherein the step of providing the field effect transistor further comprises providing a capacitive element connected between the drain region and the drain side electrode.

4. A method of high voltage operation of a field effect transistor according to claim 1 ; wherein the step of providing the field effect transistor further comprises providing a capacitive element connected between the drain region and the drain side electrode.

5. A method of high voltage operation of a field effect transistor according to claim 1 ; wherein in the step of providing the field effect transistor, the substrate comprises a semiconductor substrate.

6. A method of high voltage operation of a field effect transistor according to claim 1 ; wherein in the step of providing the field effect transistor, the substrate comprises a semiconductor thin film disposed on a surface of the supporting substrate and insulated from the supporting substrate.

7. A method of high voltage operation of a field effect transistor comprising:

providing a field effect transistor that includes a substrate, a semiconductor channel formation region disposed in a surface of the substrate, a source region and a drain region which are spaced apart from each other with the semiconductor channel formation region disposed between the source region and the drain region, a gate insulating film region disposed on the semiconductor channel formation region, a resistive gate region disposed on the gate insulating film region, a source side electrode disposed on a source region side of the resistive gate region, and a drain side electrode disposed on a drain region side of the resistive gate region;

supplying a signal electric potential to the source side electrode of the field effect transistor;

providing a bias circuit comprised of an adder having at least two inputs and one output;

supplying to one of the two inputs of the bias circuit an electric potential which changes according to an increase or decrease in a drain electric potential of the drain region of the field effect transistor;

supplying to the other of the two inputs of the bias circuit a specified electric potential; and

supplying to the drain side electrode of the field effect transistor an electric potential of the output of the adder as a bias electric potential.

8. A method of high voltage operation of a field effect transistor comprising:

providing a field effect transistor that includes a substrate, a semiconductor channel formation region disposed in a surface of the substrate, a source region and a drain region which are spaced apart from each other with the semiconductor channel formation region disposed between the source region and the drain region, a gate insulating film region disposed on the semiconductor channel formation region, a resistive gate region disposed on the gate insulating film region, a source side electrode disposed on a source region side of the resistive gate region, and a drain side electrode disposed on a drain region side of the resistive gate region;

supplying a signal electric potential to the source side electrode of the field effect transistor;

providing a bias circuit comprised of at least two serial-connected resistors;

supplying an electric potential of a high voltage power supply to one end of the two serial-connected resistors, the other end of the two serial-connected resistors being connected to the drain region of the field effect transistor; and

supplying a bias electric potential from a node between the two serial-connected resistors to the drain side electrode of the field effect transistor.

9. A method of high voltage operation of a field effect transistor comprising:

providing a field effect transistor that includes a substrate, a semiconductor channel formation region disposed in a surface of the substrate, a source region and a drain region which are spaced apart from each other with the semiconductor channel formation region disposed between the source region and the drain region, a gate insulating film region disposed on the semiconductor channel formation region, a resistive gate region disposed on the gate insulating film region, a source side electrode disposed on a source region side of the resistive gate region, and a drain side electrode disposed on a drain region side of the resistive gate region;

supplying a signal electric potential to the source side electrode of the field effect transistor;

providing a bias circuit comprised of a rectifying device and a resistor serially connected to the rectifying device, a connection end on a side of the rectifying device being connected to the drain region of the field effect transistor;

supplying a specified electric potential to a connection end on a side of the resistor; and

supplying a bias electric potential from a node between the rectifying device and the resistor to the drain side electrode of the field effect transistor.

10. A method of high voltage operation of a field effect transistor according to claim 7 ; wherein the bias electric potential supplied to the drain side electrode of the field effect transistor has an absolute value which is equal to or larger than that of a specified electric potential and which changes according to an increase or decrease in a drain electric potential.

11. A method of high voltage operation of a field effect transistor according to claim 8 ; wherein the bias electric potential supplied to the drain side electrode of the field effect transistor has an absolute value which is equal to or larger than that of a specified electric potential and which changes according to an increase or decrease in a drain electric potential.

12. A method of high voltage operation of a field effect transistor according to claim 9 ; wherein the bias electric potential supplied to the drain side electrode of the field effect transistor has an absolute value which is equal to or larger than that of a specified electric potential and which changes according to an increase or decrease in a drain electric potential.