Stage protection in multi-stage charge pumps

A method for operating a charge pump, the method comprising:

• selectively enabling a pumping function of a charge pump comprising multiple low-voltage pump stages connected in series providing a high-voltage output under steady state operation, wherein each low-voltage pump stage includes:
• a capacitor node coupled to a capacitive element;
• a low-voltage switching device comprising a dielectric layer having a threshold voltage;
• and
• an output node coupled to the capacitor node through the low-voltage switching device;
• selectively disabling the pumping function of the charge pump;
• and
• supplying a current to the capacitor nodes of two or more of the multiple pump stages using a common discharge circuit coupled between a reference voltage and a common node when the pumping function of the charge pump is disabled, the current configured to reduce charge from the two or more pump stages of the multiple pump stages through multiple high-voltage diodes, each coupled between the output node of a respective pump stage and the common node.

A charge pump comprising:

• multiple low-voltage pump stages connected in series comprising:
• a first pump stage comprising:
• a first input node;
• a first capacitor node coupled to a first capacitive element;
• a first low-voltage switching device comprising a dielectric layer having a low-voltage threshold;
• and
• a first output node coupled to the first capacitor node through the first low-voltage switching device;
• and
• a second pump stage, comprising:
• a second input node;
• a second capacitor node coupled to a second capacitive element;
• a second low-voltage switching device comprising a dielectric layer having a low-voltage threshold;
• and
• a second output node coupled to the second capacitor node through the second low-voltage switching device;
• multiple passive devices comprising:
• a first high-voltage diode comprising a dielectric layer having a high-voltage threshold higher than the low-voltage threshold, the first high-voltage diode coupled between the first output node of the first pump stage and a common node;
• and
• a second high-voltage diode comprising a dielectric layer having a high-voltage threshold higher than the low-voltage threshold, the second high-voltage diode coupled between the second output node of the second pump stage and the common node;
• and
• multiple diodes comprising:
• a first diode coupled between the first capacitor mode of the first pump stage and the first output node of the first pump stage;
• and
• a second diode coupled between the second capacitor node of the second pump stage and the second output node of the second pump stage;
• and
• a common discharge circuit comprising a current source coupled between a reference voltage and the common node,
• wherein the charge pump has an enabled state and a disabled state, wherein the multiple pump stages are configured to provide a pumping function in the enabled state, and wherein the common discharge circuit is configured to discharge the first and second pump stages through the first and second high-voltage diodes in the disabled state.