Multi-level class D amplifier

An amplifier, comprising:

• a first transistor coupled to a first voltage source node;
• a second transistor coupled to a second voltage source node, wherein the first and second transistors also couple together at an intermediate node;
• a third transistor coupled to the intermediate node;
• a fourth transistor coupled to the third transistor at a positive output node of the amplifier;
• a fifth transistor coupled to the intermediate node;
• and
• a sixth transistor coupled to the fifth transistor at a negative output node of the amplifier;
• further comprising a controller configured to, responsive to a magnitude of an input signal to be amplified being within a first voltage range:
• generate a control signal to turn on the first transistor;
• generate a control signal to keep the second transistor in an off state;
• generate control signals to reciprocally toggle on and off the third and fourth transistors;
• and
• generate control signals to reciprocally toggle on and off the fifth and sixth transistors;
• wherein the third and sixth transistors are on at the same time and wherein the fourth and the fifth transistors are on at the same time.

An amplifier, comprising:

• a first transistor coupled to a first voltage source node;
• a second transistor coupled to a second voltage source node, wherein the first and second transistors also couple together at an intermediate node;
• a third transistor coupled to the intermediate node;
• a fourth transistor coupled to the third transistor at a positive output node of the amplifier;
• a fifth transistor coupled to the intermediate node;
• and
• a sixth transistor coupled to the fifth transistor at a negative output node of the amplifier;
• further comprising a controller configured to, responsive to a magnitude of an input signal to be amplified being outside a first voltage range:
• generate control signals to reciprocally toggle on and off the first and second transistors;
• responsive to the magnitude of the input voltage being positive, generate control signals to turn on the third and sixth transistors and turn off the fourth and fifth transistors;
• and
• responsive to the magnitude of the input voltage being negative, generate control signals to turn on the fifth and fourth transistors and turn off the third and sixth transistors.

An amplifier, comprising:

• a first transistor coupled to a first voltage source node;
• a boost converter configured to convert a first voltage from the first voltage source node to a higher second voltage of a second voltage source node;
• a second transistor coupled to the second voltage source node, wherein the first and second transistors also couple together at an intermediate node;
• a third transistor coupled to the intermediate node;
• a fourth transistor coupled to the third transistor at a positive output node of the amplifier;
• a fifth transistor coupled to the intermediate node;
• a sixth transistor coupled to the fifth transistor at a negative output node of the amplifier;
• and
• a controller configured to:
• responsive to a control signal indicative of an input signal to be amplified being lower than a threshold, turn on the first transistor, turn off the second transistor, reciprocally turn on and off the third and fourth transistors, and reciprocally turn on and off the fifth and sixth transistors;
• and
• responsive to the control signal indicative of the input signal being greater than the threshold, reciprocally turn on and off the first and second transistors, responsive to the magnitude of the input voltage being positive turn on the third and sixth transistors and turn off the fourth and fifth transistors, and responsive to the magnitude of the input voltage being negative turn on the fifth and fourth transistors and turn off the third and sixth transistors.

An amplifier, comprising:

• a first voltage source node;
• a second voltage node;
• a voltage source switch network operable to switch either a voltage from the first voltage source node or the second voltage node to an intermediate node;
• a second switch network coupled to the intermediate node and operable to switch a voltage on the intermediate node or a common voltage to an output node of the amplifier;
• and
• a controller configured to:
• responsive to a control signal indicative of an input signal to be amplified being lower than a threshold, assert control signals to switch the voltage from the first voltage source node to the intermediate node, and assert control signals to the second switch network to toggle an output voltage on the output node between the common voltage and the voltage on the intermediate node;
• and
• responsive to the control signal indicative of the input signal being greater than the threshold, assert control signals to the voltage source switch network to reciprocally switch the voltages from the first source voltage node and from the second voltage node to the intermediate node and assert control signals to the second switch network to toggle an output voltage on the output node between the voltage from the first voltage source node and the voltage from the second voltage node.