Device and method for generating a temperature-independent reference voltage

1 . A voltage generator comprising:

a temperature-dependent voltage generator configured to receive a first current and a second current that is a mirror current of the first current, and to generate, based on the first and second currents, a voltage that increases with temperature, wherein the temperature-dependent voltage generator includes a first transistor stack and a second transistor stack, each of the first transistor stack and the second transistor stack has a first source/drain terminal and a gate terminal connected to each other at a temperature-dependent voltage generator node; and

a reference voltage node connected to a second source/drain terminal of the second transistor stack and configured to provide a reference voltage substantially independent of temperature.

2 . The voltage generator of claim 1 , wherein each of the first transistor stack and the second transistor stack includes a predetermined number of transistors and the number of transistors of the first transistor stack is greater than the number of transistors of the second transistor stack.

3 . The voltage generator of claim 1 , wherein the voltage generator does not include a bipolar junction transistor (BJT).

4 . The voltage generator of claim 1 , wherein the voltage generator does not include transistors that have different threshold voltages.

5 . The voltage generator of claim 1 , wherein the first and second currents are proportional to each other and flow through the temperature-dependent voltage generator node from a first current mirror circuit.

6 . The voltage generator of claim 5 , further comprising:

a resistor; and

a second current mirror circuit connected between the first current mirror circuit and the resistor and configured to generate a temperature-dependent current that is based on a mirror current of the first current mirror circuit and that flows through the resistor.

7 . The voltage generator of claim 1 , wherein the voltage generator has a temperature coefficient of less than 100 ppm/° C.

8 . A semiconductor device comprising:

a first temperature-dependent voltage generator configured to receive a first current and a second current that is a mirror current of the first current, and to generate, based on the first and second currents, a voltage that increases with temperature, wherein a first transistor module in the first temperature-dependent voltage generator has a first source/drain terminal;

a second temperature-dependent voltage generator configured to generate a voltage that decreases with temperature and including a second transistor module having a source/drain terminal and a gate terminal connected to each other and to the first source/drain terminal of the first transistor module; and

a reference voltage node connected to the first temperature-dependent voltage generator and configured to provide a reference voltage substantially independent of temperature.

9 . The semiconductor device of claim 8 , wherein the second transistor module includes:

a plurality of transistor stacks; and

a switch circuit configured to selectively connect one or more of the plurality of transistor stacks to the reference voltage node.

10 . The semiconductor device of claim 8 , wherein the first temperature-dependent voltage generator further includes a third transistor module having a first source/drain terminal connected to the reference voltage node, the semiconductor device further comprising:

a first current mirror circuit configured to generate the first and second currents that are proportional to each other and that flow through a temperature-dependent voltage node, wherein:

each of the first and third transistor modules further has a second source/drain terminal and a gate terminal connected to each other at the temperature-dependent voltage node.

11 . The semiconductor device of claim 10 , further comprising a second current mirror circuit connected to the first current mirror circuit and including a transistor connected between the reference voltage node and a supply voltage node.

12 . The semiconductor device of claim 11 , further comprising a resistor connected between the second current mirror circuit and the supply voltage node.

13 . The semiconductor device of claim 10 , wherein:

the first transistor module includes a plurality of transistors that are connected in series and that constitute a first transistor stack;

the third transistor module includes a plurality of transistors that are connected in series and that constitute a third transistor stack; and

the number of transistors of the first transistor stack is greater than the number of transistors of the third transistor stack.

14 . The semiconductor device of claim 13 , further comprising:

one or more first transistor stacks connected in parallel to the first transistor stack; and

one or more third transistor stacks connected in parallel to the third transistor stack.

15 . The semiconductor device of claim 14 , wherein the number of the first transistor stacks is the same as the number of the third transistor stacks.

16 . A method for generating a temperature-independent reference voltage, the method comprising:

receiving, by a first temperature-dependent voltage node, a first current and a second current that is a mirror current of the first current;

generating, based on the first and second currents, a first gate-to-source voltage substantially equal to a difference between a gate-to-source voltage of a first transistor module and a gate-to-source voltage of a second transistor module at the first temperature-dependent voltage generator node, wherein each of the first and second transistor modules has a gate terminal and a first source/drain terminal connected to each other at the first temperature-dependent voltage generator node;

generating, by a third transistor module, a second gate-to-source voltage; and

providing, at a reference voltage node, a temperature-independent reference voltage substantially equal to a sum of the first and second gate-to-source voltages.

17 . The method of claim 16 , further comprising generating the second gate-to-source voltage at a second temperature-dependent voltage generator node that is connected to a second source/drain terminal of the first transistor module and a gate terminal and a first source/drain terminal of the third transistor module.

18 . The method of claim 16 , wherein the first and second currents that flow through the first temperature-dependent voltage generator node are provided from a first current mirror circuit.

19 . The method of claim 18 , further comprising generating, by a second current mirror circuit connected to the first current mirror circuit, a temperature-dependent current that flows through a resistor.

20 . The method of claim 19 , wherein the second current mirror circuit includes a transistor connected between the reference voltage node and ground.