Reference voltage generator having diode-connected depletion MOS transistors with same temperature coefficient
View Patent ↗A reference voltage generator has a first N type depletion MOS transistor configured to cause a constant current to flow, and a second N type depletion MOS transistor diode-connected to the first N type depletion MOS transistor and configured to generate a reference voltage based on the constant current. The first and second N type depletion MOS transistors have the same temperature coefficient of a threshold voltage. The first N type depletion MOS transistor has a buried channel into which arsenic impurities are diffused. The second N type depletion MOS transistor has a buried channel into which phosphorous impurities are diffused.
1. A reference voltage generator, comprising:
a first N type depletion MOS transistor configured to cause a constant current to flow; and
a second N type depletion MOS transistor that is diode-connected to the first N type depletion MOS transistor, has the same temperature coefficient of a threshold voltage as a temperature coefficient of a threshold voltage of the first N type depletion MOS transistor, and is configured to generate a reference voltage based on the constant current;
wherein the second N type depletion MOS transistor has a buried channel into which phosphorous impurities are diffused, and the first N type depletion MOS transistor has a buried channel into which arsenic impurities are diffused.
2. A reference voltage generator according to claim 1 , wherein the reference voltage is a difference between the threshold voltage of the first N type depletion MOS transistor and the threshold voltage of the second N type depletion MOS transistor.
3. A semiconductor integrated circuit having the reference voltage generator according to claim 1 .
4. A reference voltage generator comprising:
a first depletion mode MOS transistor for supplying a constant current flow, the first depletion mode MOS transistor having a buried channel into which arsenic impurities are diffused; and
a second depletion mode MOS transistor having a diode connection to the first depletion mode MOS transistor, having the same temperature coefficient as that of the first depletion mode MOS transistor, having a buried channel into which phosphorous impurities are diffused, and generating a reference voltage based on a constant current.
5. A reference voltage generator according to claim 4 , wherein the reference voltage generated by the second depletion mode MOS transistor is a difference between a threshold voltage of the first depletion mode MOS transistor and a threshold voltage of the second depletion mode MOS transistor.
6. A reference voltage generator according to claim 4 , wherein the first depletion mode MOS transistor and the second depletion mode MOS transistor have the same conductivity type.
7. A semiconductor integrated circuit having the reference voltage generator according to claim 4 .