Constant-voltage circuit
View Patent ↗A constant-voltage circuit includes: first and second field-effect transistors; a first node connected to the drains of the first and second field-effect transistors; a second node connected to the gates of the first and second field-effect transistors; a bipolar transistor whose collector is connected to the second node; a resistor connected to the source of the second field-effect transistor and the collector of the bipolar transistor; and a bias circuit that is connected to the source of the second field-effect transistor and supplies a bias voltage to the base of the bipolar transistor, wherein a power supply is connected to the first node and a constant voltage is outputted from the source of the first field-effect transistor.
1. A constant-voltage circuit comprising:
first and second field-effect transistors;
a first node connected to drains of the first and second field-effect transistors;
a second node connected to gates of the first and second field-effect transistors;
a bipolar transistor whose collector is connected to the second node;
a resistor connected to a source of the second field-effect transistor and the collector of the bipolar transistor; and
a bias circuit that is connected to the source of the second field-effect transistor and supplies a bias voltage to a base of the bipolar transistor,
wherein a power supply is connected to the first node and a constant voltage is outputted from a source of the first field-effect transistor.
2. The constant-voltage circuit according to claim 1 , wherein the first and second field-effect transistors each have a gate width and a gate length so as to operate with equal current densities.
3. The constant-voltage circuit according to claim 1 , wherein the first and second field-effect transistors are depletion-type FETs.
4. The constant-voltage circuit according to claim 1 , wherein the bipolar transistor is a heterojunction bipolar transistor.
5. The constant-voltage circuit according to claim 1 , wherein the first and second field-effect transistors are pseudomorphic high electron mobility transistors.
6. The constant-voltage circuit according to claim 1 , wherein the bias circuit comprises multiple resistors.
7. The constant-voltage circuit according to claim 1 , wherein the bias circuit comprises multiple bipolar transistors.
8. The constant-voltage circuit according to claim 1 , further comprising a switch element connected to the first node and the power supply.
9. The constant-voltage circuit according to claim 8 , wherein the switch element is a third field-effect transistor.
10. The constant-voltage circuit according to claim 9 , wherein the third field-effect transistor is a depletion-type FET.
11. The constant-voltage circuit according to claim 9 , wherein the third field-effect transistor is a pseudomorphic high electron mobility transistor.