Charge pump circuit and semiconductor device including the same
View Patent ↗Efficiency of a charge pump circuit is increased. The charge pump circuit includes serially connected fundamental circuits each including a diode-connected transistor and a capacitor. At least one transistor is provided with a back gate, and the back gate is connected to any node in the charge pump circuit. For example, the charge pump circuit is of a step-up type; in which case, if the transistor is an n-channel transistor, a back gate of the transistor in the last stage is connected to an output node of the charge pump circuit. Back gates of the transistors in the other stages are connected to an input node of the charge pump circuit. In this way, the voltage holding capability of the fundamental circuit in the last stage is increased, and the conversion efficiency can be increased because an increase in the threshold of the transistors in the other stages is prevented.
1. A charge pump circuit comprising:
a first input terminal to which a first voltage is input;
a first output terminal that outputs a second voltage; and
k (k is an integer of 2 or more) stages of serially connected fundamental circuits between the first input terminal and the first output terminal,
wherein each of the fundamental circuits comprises:
a second input terminal;
a second output terminal connected to the second input terminal of the fundamental circuit in the next stage;
a transistor comprising a first electrode, a second electrode, and a gate, wherein the gate and the first electrode are connected to each other; and
a capacitor comprising a first terminal and a second terminal,
wherein the first electrode is connected to the second output terminal and the second electrode is connected to the second input terminal,
wherein the first terminal of the capacitor is connected to the second output terminal,
wherein in some of the first to (k−1)-th stages of fundamental circuits, the transistors include a back gate directly connected to the first input terminal, the others of the first to (k−1)-th stages of fundamental circuits, the transistors include a back gate directly connected to the first output terminal or/and the second output terminal, and
wherein, in the k-th stage of the k stages of fundamental circuits, the transistor includes a back gate directly connected to the first output terminal.
2. The charge pump circuit according to claim 1 , wherein in the first to (k−1)-th stages of fundamental circuits, a first clock signal input to the second terminal of the capacitor in one of the first to (k−1)-th stages and a second clock signal input to the second terminal of the capacitor in a stage adjacent to the stage have opposite phases.
3. The charge pump circuit according to claim 1 , wherein a third voltage is input to the second terminal of the capacitor of the fundamental circuit in the k-th stage.
4. The charge pump circuit according to claim 3 , wherein the third voltage is a ground potential.
5. The charge pump circuit according to claim 1 , wherein the first voltage is a ground potential and the second voltage is a negative voltage.
6. The charge pump circuit according to claim 1 ,
wherein the transistor in each of the fundamental circuits is a n-channel transistor.
7. The charge pump circuit according to claim 1 , wherein the transistor in each of the fundamental circuits includes an oxide semiconductor in which a channel is formed.
8. A semiconductor device comprising:
the charge pump circuit according to claim 1 , and
a circuit to which the second voltage generated by the charge pump circuit is supplied.
9. A semiconductor device comprising:
an antenna;
a power supply circuit;
a circuit;
a logic portion;
the charge pump circuit according to claim 1 ; and
a memory portion.
10. A charge pump circuit comprising:
a first input terminal to which a first voltage is input;
a first output terminal that outputs a second voltage; and
k (k is an integer of 2 or more) stages of serially connected fundamental circuits between the first input terminal and the first output terminal,
wherein each of the fundamental circuits comprises:
a second input terminal;
a second output terminal connected to the second input terminal of the fundamental circuit in the next stage;
a transistor comprising a first electrode, a second electrode, and a gate, wherein the gate and the first electrode are connected to each other; and
a capacitor comprising a first terminal and a second terminal,
wherein the first electrode is connected to the second input terminal and the second electrode is connected to the second output terminal,
wherein the first terminal of the capacitor is connected to the second output terminal, and
wherein in some of the first to (k−1)-th stages of fundamental circuits, the transistors include a back gate directly connected to the first input terminal, the others of the first to (k−1)-th stages of fundamental circuits, the transistors include a back gate directly connected to the first output terminal or/and the second output terminal, and
wherein, in the k-th stage of the k stages of fundamental circuits, the transistor includes a back gate directly connected to the first input terminal.
11. The charge pump circuit according to claim 10 , wherein in the first to (k−1)-th stages of fundamental circuits, a first clock signal input to the second terminal of the capacitor in one of the first to (k−1)-th stages and a second clock signal input to the second terminal of the capacitor in a stage adjacent to the stage have opposite phases.
12. The charge pump circuit according to claim 10 , wherein a third voltage is input to the second terminal of the capacitor of the fundamental circuit in the k-th stage.
13. The charge pump circuit according to claim 12 , wherein the third voltage is a ground potential.
14. The charge pump circuit according to claim 10 , wherein the first voltage is a ground potential and the second voltage is a negative voltage.
15. The charge pump circuit according to claim 10 ,
wherein the transistor in each of the fundamental circuits is an n-channel transistor.
16. The charge pump circuit according to claim 10 , wherein the transistor in each of the fundamental circuits includes an oxide semiconductor in which a channel is formed.
17. A semiconductor device comprising:
the charge pump circuit according to claim 10 , and
a circuit to which the second voltage generated by the charge pump circuit is supplied.
18. A semiconductor device comprising:
an antenna;
a power supply circuit;
a circuit;
a logic portion;
the charge pump circuit according to claim 10 ; and
a memory portion.
19. A semiconductor device comprising:
an antenna;
a logic portion;
a first circuit; and
a memory portion,
wherein the logic portion has a function of generating a signal that is transmitted from the antenna,
wherein the memory portion has a function of storing data that is processed by the logic portion,
wherein the first circuit has a function of applying a first voltage to the memory portion,
wherein the first circuit comprises:
a first input terminal;
a first output terminal;
a second circuit; and
wherein the second circuit comprising k (k is an integer of 2 or more) stages of serially connected fundamental circuits between the first input terminal and the first output terminal,
wherein each of the fundamental circuits comprises:
a second input terminal;
a second output terminal connected to the second input terminal of the fundamental circuit in the next stage;
a first transistor comprising a first electrode, a second electrode, and a gate, wherein the gate and the first electrode are connected to each other; and
a capacitor comprising a first terminal and a second terminal,
wherein the first electrode is connected to the second output terminal and the second electrode is connected to the second input terminal,
wherein the first terminal of the capacitor is connected to the second output terminal,
wherein in some of the first to (k−1)-th stages of fundamental circuits, the transistors include the back gate directly connected to the first input terminal, the others of the first to (k−1)-th stages of fundamental circuits, the transistors include the back gate directly connected to the first output terminal or/and the second output terminal, and
wherein, in the k-th stage of the k stages of fundamental circuits, the first transistor includes a back gate directly connected to the first output terminal,
wherein the memory portion comprises:
a wiring to which writing data is input;
a node configured to hold the data as a voltage; and
a second transistor by which continuity between the node and the wiring is controlled,
wherein the first transistor and the second transistor are each a transistor including an oxide semiconductor in which a channel is formed, and
wherein the first voltage is applied to a back channel of the second transistor.