Reference current or voltage generation circuit
A reference current or voltage generation circuit which forms a self feedback circuit with a plurality of transistors and generates a reference current or a reference voltage, the reference current or voltage generation circuit including a normally-on type transistor that has a gate connected to a first power supply and is connected between a node and a second power supply. Moreover, a voltage of the node is substantially equal to a voltage of the first power supply when the reference current or voltage generation circuit does not operate, and the voltage of the node fluctuates from the voltage of the first power supply toward a voltage of the second power supply by a predetermined value or more when the reference current or voltage generation circuit operates.
1 . A reference current or voltage generation circuit which forms a self feedback circuit with a plurality of transistors and generates a reference current or a reference voltage, the reference current or voltage generation circuit comprising:
a normally-on type transistor that has a gate connected to a first power supply and is connected between a node and a second power supply, wherein
a voltage of the node is substantially equal to a voltage of the first power supply when the reference current or voltage generation circuit does not operate, and
the voltage of the node fluctuates from the voltage of the first power supply toward a voltage of the second power supply by a predetermined value or more when the reference current or voltage generation circuit operates.
2 . The reference current or voltage generation circuit according to claim 1 , wherein the normally-on type transistor is turned off when a voltage difference between a source and the gate of the normally-on type transistor is equal to or more than the predetermined value.
3 . The reference current or voltage generation circuit according to claim 1 , further comprising:
a first switch which is provided between the node and the first power supply; and
a second switch which is provided between the normally-on type transistor and the second power supply,
wherein the first switch and the second switch are exclusively in a conduction state.
4 . The reference current or voltage generation circuit according to claim 1 , further comprising:
a first current mirror circuit that includes a first transistor provided in a first current path and a second transistor provided in a second current path, gates of the first and second transistors being connected each other;
a second current mirror circuit that includes a third transistor provided in the first current path and a fourth transistor provided in the second current path, gates of the third and fourth transistors being connected each other; and
a resistance element which is provided between the second transistor and one of the first power supply and the second power supply,
wherein a source of the normally-on type transistor is connected to a node to which a drain and a gate of the first transistor are connected.
5 . The reference current or voltage generation circuit according to claim 1 , further comprising:
a first current mirror circuit that includes a first transistor provided in a first current path and a second transistor provided in a second current path, gates of the first and second transistors being connected each other;
a second current mirror circuit that includes a third transistor provided in the first current path and a fourth transistor provided in the second current path, gates of the third and fourth transistors being connected each other; and
a resistance element which is provided in the first current path, the resistance element having one terminal connected to a node to which a drain of the first transistor and the gate of the second transistor are connected and another terminal connected to a node to which the first current path and the gate of the first transistor are connected,
wherein a source of the normally-on type transistor is connected to the node to which the first current path and the gate of the first transistor are connected.
6 . The reference current or voltage generation circuit according to claim 1 , further comprising:
a first current mirror circuit that includes a first transistor provided in a first current path and a second transistor provided in a second current path, gates of the first and second transistors being connected each other;
a second current mirror circuit that includes a third transistor provided in the first current path and a fourth transistor provided in the second current path, gates of the third and fourth transistors being connected each other; and
a resistance element which is provided in the first current path, the resistance element having one terminal connected to a node to which a drain of the first transistor and the gate of the second transistor are connected and another terminal connected to a node to which the first current path and the gate of the first transistor are connected,
wherein a source of the normally-on type transistor is connected to the gate of the second transistor.
7 . The reference current or voltage generation circuit according to claim 1 , further comprising:
an operational amplifier;
a first resistance element which is provided between an output of the operational amplifier and an inverting terminal of the operational amplifier;
a second resistance element which is provided between the output of the operational amplifier and a non-inverting terminal of the operational amplifier;
a first diode which is provided between the first resistance element and the first power supply, the first diode being provided in a forward direction with respect to the first power supply;
a third resistance element which is provided between the first resistance element and the first diode; and
a second diode which is provided between the second resistance element and the first power supply, the second diode being provided in a forward direction with respect to the first power supply,
wherein a source of the normally-on type transistor is connected between the second resistance element and the non-inverting terminal.