Start-up circuit for reference voltage generation circuit
View Patent ↗Embodiments relate to a start-up circuit for a reference voltage generation circuit. According to embodiments, a start-up circuit may include a start-up start unit allowing current to flow in the reference voltage generation circuit to initiate a start-up process in response to a start-up start signal, a reference current generation unit decreasing a variable voltage depending on whether the reference voltage generation circuit is started up and generating start-up reference current corresponding to the variable voltage, and a start-up controller detecting current flowing in the reference voltage generation circuit, comparing the detected result with the start-up reference current, and outputting the compared result as a start-up start signal. Current consumption may be decreased after start-up. A BRG circuit may be stably started up. If a high supply voltage is used, current consumption may decrease, and if a low supply voltage is used, a BGR circuit may be stably started up.
1. A device, comprising:
a start-up start unit configured to allow current to flow in a reference voltage generation circuit to initiate a start-up process in an initial stage of the start-up process in response to a start-up start signal;
a reference current generation unit configured to decrease a variable voltage depending on whether or not the reference voltage generation circuit is started up and generate a start-up reference current corresponding to the variable voltage; and
a start-up controller configured to detect a current flowing in the reference voltage generation circuit, compare the detected current with the start-up reference current, and output a compared result as the start-up start signal,
wherein the start-up start unit comprises a first transistor having a drain and a source connected between a control voltage to initiate the start-up process of the reference voltage generation circuit, wherein a reference voltage and a gate are connected to receive the start-up start signal, and
wherein the reference current generation unit comprises:
a second transistor having a source and a drain connected between a supply voltage and a load voltage, and a gate connected to the load voltage, the start-up reference current flowing in the second transistor; and
a third transistor having a source and a drain connected between the load voltage and the start-up start signal, and a gate connected to the detected current,
wherein the variable voltage comprises a difference between voltages across the source and the drain of the second transistor.
2. The device of claim 1 , wherein the start-up controller comprises:
a fourth transistor having a drain and a source connected between the gate of the first transistor and the reference voltage, and a gate connected to the gate of the third transistor;
a fifth transistor having a source and a drain connected between the supply voltage and the gate of the third transistor, and a gate connected to the control voltage; and
a sixth transistor having a drain and a source connected between the gate of the third transistor and the reference voltage, and a gate connected to the gate of the fourth transistor.
3. The device of claim 2 , wherein the detected current comprises a current flowing from the fifth transistor to the sixth transistor, and the start-up start signal comprises a drain voltage of the fourth transistor.
4. The device of claim 2 , wherein when the reference voltage generation circuit is started up, a level of the load voltage is increased by a sum of threshold voltages of the third and sixth transistors.
5. The device of claim 1 , wherein the reference current generation unit comprises a seventh transistor having a drain and a source connected between the supply voltage and the second transistor, and a gate connected to the control voltage.
6. The device of claim 5 , wherein, when the reference voltage generation circuit is started up, a level of the voltage supplied to the source of the second transistor becomes lower by a threshold voltage of the seventh transistor.
7. A device, comprising:
an operational amplifier;
a first transistor connected between an output terminal of the operational amplifier and a reference voltage;
a second transistor having a diode structure and connected between a supply voltage and a load voltage;
a third transistor connected between the load voltage and a gate of the first transistor;
a fourth transistor connected between the gate of the first transistor and the reference voltage;
a fifth transistor connected between the supply voltage and a gate of the third transistor and having a gate connected to an output terminal of the operational amplifier; and
a sixth transistor having a diode structure and connected between gates of the third and fourth transistors and the reference voltage.
8. The device of claim 7 , comprising a seventh transistor connected between the supply voltage and the second transistor, and having a gate connected to the output terminal of the operational amplifier.
9. The device of claim 7 , wherein the operational amplifier is configured to decrease a voltage difference between two paths, in which different currents flow, in response to an external environment condition.
10. A method, comprising:
initiating a start-up process by allowing current to flow in a reference voltage generation circuit in an initial stage of the start-up process in response to a start-up start signal using a start-up start unit;
decreasing a variable voltage depending on whether or not the reference voltage generation circuit is started up and generating a start-up reference current corresponding to the variable voltage using a reference current generation unit;
detecting a current flowing in the reference voltage generation circuit, comparing the detected current with the start-up reference current, and outputting a compared result as the start-up start signal using a start-up controller;
providing an operational amplifier;
providing a first transistor connected between an output terminal of the operational amplifier and a reference voltage;
providing a second transistor having a diode structure and connected between a supply voltage and a load voltage;
providing a third transistor connected between the load voltage and a gate of the first transistor;
providing a fourth transistor connected between the gate of the first transistor and the reference voltage;
providing a fifth transistor connected between the supply voltage and a gate of the third transistor and having a gate connected to an output terminal of the operational amplifier; and
providing a sixth transistor having a diode structure and connected between gates of the third and fourth transistors and the reference voltage.
11. The method of claim 10 , wherein the start-up start unit comprises a first transistor having a drain and a source connected between a control voltage to initiate the start-up process of the reference voltage generation circuit, wherein a reference voltage and a gate connected to receive the start-up start signal.
12. The method of claim 11 , wherein the reference current generation unit comprises:
a second transistor having a source and a drain connected between a supply voltage and a load voltage, and a gate connected to the load voltage, the start-up reference current flowing in the second transistor; and
a third transistor having a source and a drain connected between the load voltage and the start-up start signal and a gate connected to the detected current,
wherein the variable voltage comprises a difference between voltages across the source and the drain of the second transistor.
13. The method of claim 12 , wherein the start-up controller comprises:
a fourth transistor having a drain and a source connected between the gate of the first transistor and the reference voltage, and a gate connected to the gate of the third transistor;
a fifth transistor having a source and a drain connected between the supply voltage and the gate of the third transistor, and a gate connected to the control voltage; and
a sixth transistor having a drain and a source connected between the gate of the third transistor and the reference voltage, and a gate connected to the gate of the fourth transistor.
14. The method of claim 13 , wherein the detected current comprises a current flowing from the fifth transistor to the sixth transistor, and the start-up start signal comprises a drain voltage of the fourth transistor.
15. The method of claim 13 , comprising increasing a level of the load voltage by a sum of threshold voltages of the third and sixth transistors when the reference voltage generation circuit is started up.
16. The method of claim 12 , wherein the reference current generation unit comprises a seventh transistor having a drain and a source connected between the supply voltage and the second transistor, and a gate connected to the control voltage.
17. The method of claim 16 , comprising lowering a level of the voltage supplied to the source of the second transistor by a threshold voltage of the seventh transistor when the reference voltage generation circuit is started up.