Patent ID: 6072358
Filing Date: 2000-06-06
Classification: G11C

Abstract:
A charge pump circuit comprising:a pass transistor having a first source/drain terminal coupled to a source of high voltage, a second source/drain terminal and a gate terminal;an enable transistor having a first source/drain terminal coupled to receive an enable input, a gate terminal coupled to a control signal, and a second source/drain terminal coupled to an enable node;a first pump capacitor having a first terminal coupled to a pump node and a second terminal coupled to receive a pump input;a pump transistor coupled between the pump node and the enable node and configured to pump a voltage at the gate terminal of the pass transistor to a voltage larger than the high voltage when activated in response to an enable signal on the enable input;a first isolation transistor coupled between the enable node and the gate terminal of the pass transistor, and configured to isolate the gate terminal of the pass transistor from the enable node when the charge pump circuit is not enabled;a second isolation transistor coupled between the second source/drain terminal of the pass transistor and the pump node, and configured to isolate the second source/drain terminal of the pass transistor from the pump node when the charge pump circuit is not enabled; anda bias circuit coupled to the gate terminal of the pass transistor and configured to raise a voltage at the gate terminal of the pass transistor to reduce oxide stress when the pump circuit is disabled in response to the enable signal.