Supply voltage generating circuit and semiconductor device having the same
View Patent ↗A supply voltage generating circuit includes a first charge pump circuit that generates a first internal supply voltage, and second charge pump circuit that generates a second internal supply voltage. The absolute value of the second internal supply voltage is greater than that of the first internal supply voltage. The output terminal of the first charge pump circuit is connected to a secondary-side charging terminal of the second charge pump circuit. The secondary-side is an output-side of the corresponding charge pump circuit, and the charging terminal is an auxiliary charging terminal that supplies an auxiliary charge to a secondary-side output terminal of the corresponding charge pump circuit. The output terminal of the second charge pump circuit outputs a voltage value that is the result of adding a prescribed voltage value to the value of the first internal supply voltage applied to the charging terminal.
1. A semiconductor device comprising:
a capacitor including first and second electrodes;
a first transistor circuit configured to supply a pumping signal to the first electrode of the capacitor, the pumping signal being changed between a first potential and a second potential different from the first potential; and
a second transistor circuit configured to precharge the second electrode of the capacitor to a third potential different from the first and second potentials so that the second electrode of the capacitor is changed from the third potential to a fourth potential higher than the third potential when the pumping signal is changed from the first potential to the second potential.
2. The semiconductor device as claimed in claim 1 , further comprising:
a terminal supplied with the second potential, the first terminal being operatively connected to the first electrode of the capacitor; and
a terminal supplied with the third potential, the second terminal being operatively connected to the second electrode of the capacitor.
3. The semiconductor device as claimed in claim 2 , wherein the first transistor circuit includes:
a first transistor electrically connected between the first terminal and the first electrode of the capacitor; and
a second transistor electrically connected between the second electrode of the capacitor and a third terminal supplied with the first potential.
4. The semiconductor device as claimed in claim 3 , wherein the second transistor circuit includes:
a third transistor electrically connected between the second terminal and the second electrode of the capacitor; and
a fourth transistor electrically connected between the second electrode of the capacitor and an output node.
5. The semiconductor device as claimed in claim 4 , wherein the second and third transistors are on and the first and fourth transistors are off during a first period, and the first and fourth transistors are on and the second and third transistors are off during a second period different from the first period.
6. The semiconductor device as claimed in claim 1 , further comprising:
an oscillator configured to produce a signal including a first level during a first period and a second level during a second period, the first and second periods being alternatively repeated; and
an output node, wherein
the second potential is higher than the first potential,
during the first period, the first transistor circuit supplies the pumping signal having the first potential to the first electrode of the first capacitor and the second transistor circuit precharges the second electrode of the first capacitor to the third potential, and
during the second period, the first transistor circuit supplies the pumping signal having the second potential to the first electrode of the first capacitor so that the second electrode of the capacitor is boosted from the third potential to the fourth potential.
7. The semiconductor device as claimed in claim 6 , the device further comprising:
a comparator configured to compare a reference voltage and a voltage on the output node to control activation or inactivation of the oscillator.
8. A semiconductor device comprising:
a capacitor including first and second electrodes;
a first terminal supplied with a first potential;
a second terminal supplied with a second potential lower than the first potential;
a third terminal supplied with a third potential higher than the second potential;
an output node;
a first transistor coupled between the first terminal as a charge pumping circuit and the first electrode of the capacitor, rendered ON during a first period and rendered off during a second period different from the first period;
a second transistor coupled between the first electrode of the capacitor and the second terminal, rendered ON during the second period and rendered Off during the first period;
a third transistor coupled between the third terminal and the second electrode of the capacitor as a pre-charging circuit, rendered On during the second period and rendered Off during the first period; and
a fourth transistor coupled between the second electrode of the capacitor and the fourth terminal, rendered On during the first period and rendered Off during the second period.
9. The semiconductor device as claimed in claim 8 , the device further comprising:
an oscillator configured to produce a signal applied to the first to forth transistors.
10. The semiconductor device as claimed in claim 9 , the device further comprising:
a comparator configured to compare a reference voltage and a voltage on the output node to control activation or inactivation of the oscillator.