Reference voltage generator

Claim 2

A reference voltage generator having a constant current source for generating a current having a small power source voltage dependency and a positive temperature dependency, and a load circuit connected to said constant current source so as to generate a reference voltage according to the current of said constant current source, said constant current source comprising: a current mirror circuit composed of a plurality of MOS transistors; first and second loads connected to said current mirror circuit so as to determine a current value of said constant current source, wherein said first load comprises a first MOS transistor which is diode-connected to a power source, said second load comprises a second MOS transistor having a gate connected to a gate and a drain of said first MOS transistor, and a resistor intervened between said second MOS transistor and said power source, said current mirror circuit has functions of inputting a drain current of said second MOS transistor and supplying a drain current to said first MOS transistor with a constant mirror ratio so as to determine a current value of said constant current source, and said load circuit comprises a combination of series-parallel connection of a plurality of MOS transistors each of which is diode-connected and is selected in size so as to set a value of the reference voltage and so as to cancel the positive temperature dependency of the current of said constant current source.

Claim 3

A reference voltage generator having a constant current source for generating a current having a small power source voltage dependency and a positive temperature dependency, and a load circuit connected to said constant current source so as to generate a reference voltage according to the current of said constant current source, said constant current source comprising: a first first-conductive type MOS transistor having a source connected to a first power source; a second first-conductive type MOS transistor having a source connected to said first power source; a third first-conductive type MOS transistor having a gate connected to a gate of said first first-conductive type MOS transistor and a gate and a drain of said second first-conductive type MOS transistor and a source connected to said first power source; a first second-conductive type MOS transistor intervened between a second power source and a drain of said first first-conductive type MOS transistor so as to be diode-connected in a forward direction; a second second-conductive type MOS transistor having a drain connected to the drain of said second first-conductive type MOS transistor and a gate connected to a gate of said first second-conductive type MOS transistor; a resistor having a resistance having a smaller temperature dependency than a temperature dependency of a threshold voltage of said first and second second-conductive type MOS transistors, and being intervened between the source of said second second-conductive type MOS transistor and said second power source; a third second-conductive type MOS transistor intervened between said second power source and the drain of said third first-conductive type MOS transistor so as to be diode-connected in a forward direction; and a fourth second-conductive type MOS transistor having a gate connected to the gate of said third second-conductive type MOS transistor, a source connected to said second power source and a drain for outputting the current of said constant current source, wherein said load circuit comprises a combination of series-parallel connection of a plurality of MOS transistors each of which is diode-connected and is selected in size so as to set a value of the reference voltage and so as to cancel the positive temperature dependency of the current of said constant current source.

Claim 4

A reference voltage generator having a constant current source for generating a current having a small power source voltage dependency and a positive temperature dependency, and a load circuit connected to said constant current source so as to generate a reference voltage according to the current of said constant current source, said constant current source comprising: a first first-conductive type MOS transistor having a source connected to a first power source; a second first-conductive type MOS transistor having a source connected to said first power source; a third first-conductive type MOS transistor having a gate connected to a gate of said first first-conductive type MOS transistor and a gate and a drain of said second first-conductive type MOS transistor and a source connected to said first power source; a first second-conductive type MOS transistor intervened between a second power source and a drain of said first first-conductive type MOS transistor so as to be diode-connected in a forward direction; a second second-conductive type MOS transistor having a drain connected to the drain of said second first-conductive type MOS transistor and a gate connected to a gate of said first second-conductive type MOS transistor; a resistor having a resistance having a smaller temperature dependency than a temperature dependency of a threshold voltage of said first and second second-conductive type MOS transistors, and being intervened between the source of said second second-conductive type MOS transistor and said second power source; a third second-conductive type MOS transistor intervened between said second power source and the drain of said third first-conductive type MOS transistor so as to be diode-connected in a forward direction; and a fourth second-conductive type MOS transistor having a gate connected to the gate of said third second-conductive type MOS transistor, a source connected to said second power source and a drain for outputting the current of said constant current source, wherein said load circuit comprises a combination of series-parallel connection of a plurality of MOS transistors each of which is diode-connected and is selected in size so as to set a value of the reference voltage and so as to cancel the positive temperature dependency of the current of said constant current source.

Claim 5

The reference voltage generator of claim 2, wherein said first first-conductive type MOS transistor comprises: a plurality of sub MOS transistors connected in parallel to one another; and a plurality of fuses for trimming which are respectively intervened in current paths of said plural sub MOS transistors.

Claim 6

The reference voltage generator of claim 3, wherein respective wirings between said plural sub MOS transistors and said plural fuses are shielded from a substrate on which said reference voltage generator is fabricated and from other signal wirings with a conductor having a potential of said second power source.

Claim 7

The reference voltage generator of claim 2, wherein said second first-conductive type MOS transistor comprises: a plurality of sub MOS transistors connected in parallel to one another; and a plurality of fuses for trimming which are respectively intervened in current paths of said plural sub MOS transistors.

Claim 8

The reference voltage generator of claim 5, wherein respective wirings between said plural sub MOS transistors and said plural fuses are shielded from a substrate on which said reference voltage generator is fabricated and from other signal wirings with a conductor having a potential of said first power source.

Claim 9

The reference voltage generator of claim 2, wherein said resistor is made of a polysilicon to which impurity is heavily doped so that said resistor has a resistance having a small temperature dependency.

Claim 10

The reference voltage generator of claim 2, wherein said resistor and a wiring between said resistor and the source of said second second-conductive type MOS transistor are respectively shielded from a substrate on which said reference voltage generator is fabricated and from other signal wirings with a conductor having a potential of said second power source.

Claim 11

The reference voltage generator of claim 2, wherein a part of the plural MOS transistors composing said load circuit comprises: a plurality of sub MOS transistors connected in parallel to one another; and a plurality of fuses for trimming which are respectively intervened in current paths of said plural sub MOS transistors.

Claim 12

The reference voltage generator of claim 2, wherein a part of the plural MOS transistors composing said load circuit comprises: a plurality of sub MOS transistors connected in series to one another; and a plurality of fuses for trimming which are respectively intervened between sources and drains of said plural sub MOS transistors.

Claim 13

The reference voltage generator of claim 2, wherein a potential of an output wiring of the reference voltage is fixed to a potential of said first power source so as to shield the output wiring from a substrate on which said reference voltage generator is fabricated and from other signal wirings.

Claim 14

The reference voltage generator of claim 2, wherein said constant current source further comprises: a fifth second-conductive type MOS transistor intervened between said second power source and the drain of said second first-conductive type MOS transistor; and an inverter circuit for detecting a potential of the gate of said first second-conductive type MOS transistor and for controlling a potential of the gate of said fifth second-conductive type MOS transistor according to the thus detected potential.

Claim 15

The reference voltage generator of claim 12, wherein said inverter circuit comprises: a sixth second-conductive type MOS transistor current-mirror-connected to said first second-conductive type MOS transistor; and a load intervened between said first power source and the drain of said sixth second-conductive type MOS transistor so as to control the potential of the gate of said fifth second-conductive type MOS transistor.

Claim 16

The reference voltage generator of claim 2, wherein said constant current source further comprises: a seventh second-conductive type MOS transistor having a gate connected to the drain of said fourth second-conductive type MOS transistor, and intervened between the drain of said first first-conductive type MOS transistor and the drain of said second first-conductive type MOS transistor.

Claim 17

A constant current source, comprising: a first first-conductive type MOS transistor having a source connected to a first power source; a second first-conductive type MOS transistor having a source connected to said first power source; a first second-conductive type MOS transistor intervened between a second power source and a drain of said first first-conductive type MOS transistor so as to be diode-connected in a forward direction; a second second-conductive type MOS transistor having a drain connected to a drain of said second first-conductive type MOS transistor, a gate connected to a gate of said first second-conductive type MOS transistor and a source connected to said second power source; a third second-conductive type MOS transistor intervened between said second power source and the drain of said second first-conductive type MOS transistor; and an inverter circuit for detecting a potential of the gate of said first second-conductive type MOS transistor and for controlling a potential of a gate of said third second-conductive type MOS transistor according to the thus detected potential.

Claim 18

A constant current source, comprising: a first first-conductive type MOS transistor having a source connected to a first power source; a second first-conductive type MOS transistor having a source connected to said first power source; a first second-conductive type MOS transistor intervened between a second power source and a drain of said first first-conductive type MOS transistor so as to be diode-connected in a forward direction; a second second-conductive type MOS transistor having a drain connected to a drain of said second first-conductive type MOS transistor, a gate connected to a gate of said first second-conductive type MOS transistor and a source connected to said second power source; a third second-conductive type MOS transistor intervened between said second power source and the drain of said second first-conductive type MOS transistor; and an inverter circuit for detecting a potential of the gate of said first second-conductive type MOS transistor and for controlling a potential of a gate of said third second-conductive type MOS transistor according to the thus detected potential.

Claim 19

The constant current source of claim 15, wherein said inverter circuit comprises: a fourth second-conductive type MOS transistor current-mirror-connected to said first second-conductive type MOS transistor; and a load intervened between said first power source and the drain of said fourth second-conductive type MOS transistor so as to control the potential of the gate of said third second-conductive type MOS transistor.