Inverting buck-boost using single-inductor boost and charge pump with a grounded switch

A system for supplying a regulated inverted voltage to a load, where the regulated inverted voltage has a magnitude greater or less than the magnitude of an input voltage with a predetermined positive range of voltages, comprising:

• a supply of the input voltage;
• a boost stage including a boost inductor coupled between a source of the input voltage and a switch node;
• a charge pump stage including a charge pump capacitor and a charge transfer network, the charge pump capacitor coupled between the switch node and a pump node, which is coupled by the charge transfer network to an output node coupled, and a positive voltage reference;
• an output capacitor coupled to the output node in parallel with the load;
• and
• switching circuitry including one of (i) a transistor switch coupled between the switch node and ground, and (ii) circuitry configured to couple a transistor switch from the switch node to ground;
• the switching circuitry configured to switch between a first phase in which the transistor switch conducts to connect the switch node to ground, and a second phase in which the transistor switch is non-conducting to disconnect the switch node from ground, and
• the switching circuitry (i) operable in the first phase, to transfer energy to the grounded boost inductor from the input voltage source, and to transfer energy from the grounded charge pump capacitor through the charge transfer network to the output node, and (ii) operable in the second phase, to transfer energy from the boost inductor to the charge pump capacitor which is clamped at the pump node to the reference voltage by the charge transfer network;
• thereby enabling a regulated inverted output voltage to be supplied to the output capacitor and the load.

A method for supplying a regulated voltage to a load by converting an input voltage with a predetermined range into a regulated inverted output voltage with a magnitude greater or less than the magnitude of the input voltage, comprising:

• configuring an inverting boost-buck converter topology with a boost stage coupled to a charge pump stage at a switch node controlled by a transistor switch coupled between the switch node and ground, the boost stage including a boost inductor coupled between an input voltage supply and the switch node, and the charge pump stage including a charge pump capacitor coupled between the switch node and a pump node which is coupled to the load and an output capacitor in parallel with the load;
• and
• in a first phase, switching the transistor switch conducting to couple the switch node to ground, and thereby (i) transferring energy from the input voltage supply to the boost inductor, and (ii) transferring energy from the charge pump capacitor to the output node, and
• in a second phase, switching the transistor switch to non-conducting (decoupling the switch node from ground), and clamping the charge pump capacitor to a reference voltage, and thereby transferring energy from the boost inductor to the charge pump capacitor;
• thereby enabling the regulated inverted output voltage to be supplied to the output capacitor and the load.