Leakage current blocking circuit and leakage current blocking method for decoupling capacitor

1. A leakage current blocking circuit for a decoupling capacitor, wherein a first end of the decoupling capacitor is coupled to a power voltage, the leakage current blocking circuit is coupled between a second end of the decoupling capacitor and a ground voltage, and the leakage current blocking circuit comprises:

at least one switch used to provide a channel allowing the decoupling capacitor to be coupled to the ground voltage when the decoupling capacitor is not damaged; wherein the at least one switch is turned off to block a leakage current of the decoupling capacitor when the decoupling capacitor is damaged;

wherein the at least one switch is a first N-type MOSFET, a drain of the first N-type MOSFET is coupled to the second end of the decoupling capacitor, and a source of the first N-type MOSFET is coupled to the ground voltage;

wherein the leakage current blocking circuit further includes:

a second N-channel depletion-mode MOSFET, wherein a drain of the second N-channel depletion-mode MOSFET and the drain of the first N-type MOSFET are commonly coupled to the second end of the decoupling capacitor via a first node; and a source of the second N-channel depletion-mode MOSFET and a gate of the second N-channel depletion-mode MOSFET are commonly coupled to a second node; and

an inverter, wherein an input end of the inverter is coupled to the second node, and an output end of the inverter is coupled to a gate of the first N-type MOSFET.

2. The leakage current blocking circuit according to claim 1 , further comprising:

a capacitor, wherein a first end of the capacitor is coupled to the second node, and a second end of the capacitor is coupled to the ground voltage; and

a third N-channel depletion-mode MOSFET, wherein a drain of the third N-channel depletion-mode MOSFET and the first end of the capacitor are commonly coupled to the second node, and a source of the third N-channel depletion-mode MOSFET and a gate of the third N-channel depletion-mode MOSFET are commonly coupled to the ground voltage.

3. The leakage current blocking circuit according to claim 2 , wherein, when the decoupling capacitor is not damaged, a first current flowing through the second N-channel depletion-mode MOSFET is smaller than a second current flowing through the third N-channel depletion-mode MOSFET, the output end of the inverter outputs a high-voltage signal since the input end of the inverter inputs a low-voltage signal, and the high-voltage signal is used to turn on the first N-type MOSFET for allowing the decoupling capacitor to be coupled to the ground voltage via the drain of the first N-type MOSFET and the source of the first N-type MOSFET.

4. The leakage current blocking circuit according to claim 2 , wherein, when the decoupling capacitor is damaged, a first current flowing through the second N-channel depletion-mode MOSFET is greater than a second current flowing through the third N-channel depletion-mode MOSFET, the output end of the inverter outputs a low-voltage signal since the input end of the inverter inputs a high-voltage signal, and the low-voltage signal is used to turn off the first N-type MOSFET to block the leakage current of the decoupling capacitor.

5. A leakage current blocking method for a decoupling capacitor, wherein a first end of the decoupling capacitor is coupled to a power voltage, and the leakage current blocking method comprises:

providing a leakage current blocking circuit coupled between a second end of the decoupling capacitor and a ground voltage, wherein, at least one switch of the leakage current blocking circuit is used to provide a channel allowing the decoupling capacitor to be coupled to the ground voltage when the decoupling capacitor is not damaged; and

the at least one switch of the leakage current blocking circuit being turned off so as to block a leakage current of the decoupling capacitor when the decoupling capacitor is damaged;

wherein the at least one switch is a first N-type MOSFET, a drain of the first N-type MOSFET is coupled to the second end of the decoupling capacitor, and a source of the first N-type MOSFET is coupled to the ground voltage;

wherein the leakage current blocking circuit further includes:

a second N-channel depletion-mode MOSFET, wherein a drain of the second N-channel depletion-mode MOSFET and the drain of the first N-type MOSFET are commonly coupled to the second end of the decoupling capacitor via a first node; and a source of the second N-channel depletion-mode MOSFET and a gate of the second N-channel depletion-mode MOSFET are commonly coupled to a second node; and

an inverter, wherein an input end of the inverter is coupled to the second node, and an output end of the inverter is coupled to a gate of the first N-type MOSFET.

6. The leakage current blocking method according to claim 5 , wherein the leakage current blocking circuit further comprises:

a capacitor, wherein a first end of the capacitor is coupled to the second node, and a second end of the capacitor is coupled to the ground voltage; and

a third N-channel depletion-mode MOSFET, wherein a drain of the third N-channel depletion-mode MOSFET and the first end of the capacitor are commonly coupled to the second node, and a source of the second N-channel depletion-mode MOSFET and a gate of the second N-channel depletion-mode MOSFET are commonly coupled to the inverter input node.

7. The leakage current blocking method according to claim 6 , wherein, when the decoupling capacitor is not damaged, a first current flowing through the second N-channel depletion-mode MOSFET is smaller than a second current flowing through the third N-channel depletion-mode MOSFET, the output end of the inverter outputs a high-voltage signal since the input end of the inverter inputs a low-voltage signal, and the high-voltage signal is used to turn on the first N-type MOSFET for allowing the decoupling capacitor to be coupled to the ground voltage via the drain of the first N-type MOSFET and the source of the first N-type MOSFET.

8. The leakage current blocking method according to claim 6 , wherein, when the decoupling capacitor is damaged, a first current flowing through the second N-channel depletion-mode MOSFET is greater than a second current flowing through the third N-channel depletion-mode MOSFET, the output end of the inverter outputs a low-voltage signal since the input end of the inverter inputs a high-voltage signal, and the low-voltage signal is used to turn off the first N-type MOSFET to block the leakage current of the decoupling capacitor.