Negative charge pump circuit

A method for controlling a negative charge pump circuit circuit, comprising:

• coupling a first electrode of a first capacitor alternately to a first node configured to receive a positive power supply potential and to a second node configured to receive a reference potential;
• coupling a second electrode of the first capacitor alternately to the second node and to a third node configured to provide a negative power supply potential;
• in a first phase of operation, alternately coupling the first and second electrodes of the first capacitor to the first and second nodes, respectively, and coupling the first and second electrodes of the first capacitor to the second and third nodes, respectively;
• in a second phase of operation, coupling the first electrode of the first capacitor to the second node and alternately coupling the second electrode of the first capacitor to the second and to the third node to thereby discharge the third node and decrease an absolute value of the negative power supply potential;
• coupling a first electrode of a second capacitor alternately to the first and second node;
• coupling the second electrode of the second capacitor alternately to the second node and third nodes;
• in the first phase of operation, coupling of the first and second electrodes of the second capacitor, respectively, to the second and third nodes when the first and second electrodes of the first capacitor are respectively coupled to the first and second nodes, the coupling of the first and second electrodes of the second capacitor being in phase opposition with the coupling of the first and second electrodes of the first capacitor, and coupling the first and second electrodes of the second capacitor, respectively, to the first and second nodes when the first and second electrodes of the first capacitor are respectively coupled to the second and third nodes;
• and
• in the second phase of operation, coupling the first electrode of the second capacitor to the second node and alternately coupling, in phase opposition with the coupling of the second electrode of the first capacitor, the second electrode of the second capacitor to the third node when the second electrode of the first capacitor is coupled to the second node and to the second node when the second electrode of the first capacitor is coupled to the third node.

A negative charge pump circuit comprising:

• switching circuitry configured to control coupling of first and second electrodes of a first capacitor to a positive power supply potential, a reference potential, or a negative power supply potential, the switching circuitry configured in a first phase of operation to alternately control coupling of the first and second electrodes of the first capacitor to the positive power supply potential and the reference potential, and in a second configuration to couple the first and second electrodes of the first capacitor to the reference potential and negative power supply potential, respectively, and the switching circuitry further configured in a second phase of operation to couple the first electrode of the first capacitor to the reference potential and to alternately couple the second electrode of the first capacitor to the reference potential and the negative power supply potential to decrease an absolute value of the negative power supply potential;
• a node configured to receive a clock signal and a node configured to receive an operating mode selection signal, the clock signal defining a switching frequency in the first phase of operation and the switching frequency in the second phase of operation;
• and
• a node configured to receive an operating mode selection signal defining the duration of the first and second phases of operation;
• and
• a first operating mode selection circuit configured to provide a control signal in the first phase of operation that is substantially identical to the clock signal in response to the operating mode selection signal being in a first state, and configured to provide a fixed control signal that causes the switching circuitry to couple the first electrode of the first capacitor to the second node in response to the operating mode selection signal being in a second state.