Control circuit for a polarity inverting buck-boost DC-DC converter

An apparatus comprising:

• a first control circuit that senses the voltage difference between a first and a second terminal;
• an error amplifier that is coupled to the second terminal and ground;
• a first amplifier that is coupled to the second terminal and ground;
• a compensation capacitance that is coupled to the first amplifier, wherein the compensation capacitance receives an output from the first amplifier, and wherein the compensation capacitance includes:
• a first capacitor that is coupled to the first amplifier;
• a first switch coupled to the first amplifier and the first capacitor;
• a continuous-discontinuous mode detection circuit that controls the switch;
• and
• a second capacitor coupled to the first switch, wherein the first capacitor has a lower capacitance than the second capacitor;
• and
• a voltage-to-current converter that is coupled to the compensation capacitance;
• a summing node that receives currents from the voltage-to-current converter, the first control circuit, and the error amplifier;
• a switched capacitance coupled to the summing node;
• and
• a second amplifier coupled to the switched capacitance.

An apparatus comprising:

• an input circuit coupled to a first terminal, a second terminal, and ground;
• a first amplifier that is coupled to the second terminal and ground;
• a compensation capacitance that is coupled to the first amplifier, wherein the compensation capacitance receives an output from the first amplifier, and wherein the compensation capacitance includes:
• a first capacitor that is coupled to the first amplifier;
• a first switch coupled to the first amplifier and the first capacitor;
• a continuous-discontinuous mode detection circuit that controls the switch;
• a second capacitor coupled to the first switch, wherein the first capacitor has a lower capacitance than the second capacitor;
• a voltage-to-duty cycle conversion circuit that is coupled to the first capacitor and the first switch, wherein the voltage-to-duty cycle conversion circuit outputs a signal to the continuous-discontinuous mode detection circuit;
• a second amplifier with an input coupled to the first capacitor and an output coupled to the second capacitor;
• and
• an output circuit coupled to the compensation capacitance and the input circuit.