Level detector, voltage generator, and semiconductor device
A level detector, a voltage generator, and a semiconductor device are provided. The voltage generator includes a level detector that senses the level of an output voltage to output a sensing signal and a voltage generating unit that generates the output voltage in response to the sensing signal. The level detector may include a first reference voltage generator configured to divide a first voltage and to output a first reference voltage, a second reference voltage generator configured to divide a second voltage in response to the output voltage and to output a second reference voltage that varies as a function of temperature, and a differential amplifier configured to receive the first and second reference voltages and to output a sensing signal in response to a sensing voltage generated by amplifying a difference between the first and second reference voltages.
1. A level detector comprising:
a first reference voltage generator configured to divide a first voltage and to output a first reference voltage;
a second reference voltage generator configured to divide a second voltage in response to a detected voltage and to output a second reference voltage that varies as a function of temperature; and
a differential amplifier configured to receive the first reference voltage and the second reference voltage and to output a sensing signal in response to a sensing voltage generated by amplifying a difference between the first reference voltage and the second reference voltage,
wherein the first voltage is a variable voltage whose voltage level increases when the temperature decreases, and the second voltage is a variable voltage whose voltage level decreases when the temperature decreases.
2. A voltage generator comprising:
a level detector configured to sense the level of an output voltage and to output a sensing signal; and
a voltage generating unit configured to generate the output voltage in response to the sensing signal,
wherein the level detector includes:
a first reference voltage generator configured to divide a first voltage and to output a first reference voltage;
a second reference voltage generator configured to divide a second voltage in response to the output voltage and to output a second reference voltage that varies as a function of temperature; and
a differential amplifier configured to receive the first reference voltage and the second reference voltage and to output a sensing signal in response to a sensing voltage generated by amplifying a difference between the first reference voltage and the second reference voltage.
3. The voltage generator according to claim 2 , wherein the output voltage is a substrate bias voltage.
4. The voltage generator according to claim 3 , wherein the voltage generating unit comprises:
an oscillator configured to output an oscillation signal in response to the sensing signal, and
a charge pump configured to pump charges in response to the oscillation signal to decrease the output voltage.
5. The voltage generator according to claim 4 , wherein the second reference voltage generator comprises:
a first PMOS transistor connected between the second voltage and a terminal that outputs the second reference voltage and has a gate that receives the second reference voltage and that has a drain-source resistance that does not vary as a function of temperature; and
a second PMOS transistor connected between the terminal that outputs the second reference voltage and a ground voltage and has a gate that receives the output voltage and that has a drain-source resistance that decreases when the temperature decreases.
6. The voltage generator according to claim 5 , wherein the first voltage and the second voltage are at a constant voltage that do not vary as a function of temperature.
7. The voltage generator according to claim 5 , wherein the first voltage is a constant voltage that does not vary as a function of temperature, and the second voltage is a variable voltage that decreases when the temperature decreases.
8. The voltage generator according to claim 5 , wherein the first voltage is a variable voltage that increases when the temperature decreases, and the second voltage is a constant voltage that does not vary as a function of temperature.
9. The voltage generator according to claim 5 , wherein the first voltage is a variable voltage that increases when the temperature decreases, and the second voltage is a variable voltage that decreases when the temperature decreases.
10. A semiconductor device comprising:
a voltage generator comprising:
a level detector configured to sense a level of an output voltage and to output a sensing signal; and
a voltage generating unit configured to generate the output voltage in response to the sensing signal,
wherein the level detector includes:
a first reference voltage generator configured to divide a first voltage and to output a first reference voltage;
a second reference voltage generator configured to divide a second voltage in response to the output voltage and to output a second reference voltage that varies as a function of temperature; and
a differential amplifier configured to receive the first reference voltage and the second reference voltage and to output a sensing signal in response to a sensing voltage that is generated by amplifying a difference between the first reference voltage and the second reference voltage.
11. The semiconductor device according to claim 10 , further comprising:
a memory cell array including at least one memory cell connected between a word line and a bit line,
wherein each of the at least one memory cell includes a cell transistor, and the output voltage is applied to the cell transistor as a substrate bias voltage.
12. The semiconductor device according to claim 11 , further comprising:
a sense amplifier having at least one NMOS sense amplifier that includes a plurality of NMOS transistors and is configured to sense and to amplify a signal on a corresponding bit line,
wherein the output voltage is applied to the NMOS transistor as a substrate bias voltage.
13. The semiconductor device according to claim 10 , wherein the output voltage is a substrate bias voltage.
14. The semiconductor device according to claim 13 , wherein the voltage generating unit comprises:
an oscillator configured to output an oscillation signal in response to the sensing signal; and
a charge pump configured to pump charges in response to the oscillation signal to decrease the output voltage.
15. The semiconductor device according to claim 14 , wherein the second reference voltage generator comprises:
a first PMOS transistor that is connected between the second voltage and a terminal that outputs the second reference voltage, has a gate that receives the second reference voltage and that has a drain-source resistance that does not vary as a function of temperature; and
a second PMOS transistor that is connected between the terminal that outputs the second reference voltage and a ground voltage, has a gate that receives the output voltage and that has a drain-source resistance that decreases when the temperature decreases.
16. The semiconductor device according to claim 15 , wherein the first voltage and the second voltage are at a constant voltage that does not vary as a function of temperature.
17. The semiconductor device according to claim 15 , wherein the first voltage is at a constant voltage that does not vary as a function of temperature, and the second voltage is a variable voltage that decreases when the temperature decreases.
18. The semiconductor device according to claim 15 , wherein the first voltage is a variable voltage that increases when the temperature decreases, and the second voltage is a constant voltage that does not vary as a function of temperature.
19. The semiconductor device according to claim 15 , wherein the first voltage is a variable voltage that increases when the temperature decreases, and the second voltage is a variable voltage that decreases when the temperature decreases.