Amplifier with reduced power consumption and improved slew rate

A supply-sensing amplifier with a folded-cascode output, the supply-sensing amplifier comprising:

• a first differential transistor pair configured to receive a differential input signal at respective input nodes and in response conduct a differential first current to a cascode-protected output node;
• a second differential transistor pair configured to receive information about the differential input signal;
• a third differential transistor pair configured to receive information about the differential input signal;
• and
• a cascode output including first and second cascode transistors, and each of the first and second cascode transistors is configured to receive a cascode control signal, wherein the cascode control signal corresponds to a magnitude of the differential input signal and is based on signals conducted by a first transistor from the second differential transistor pair and by a first transistor from the third differential transistor pair.

A method for amplifying a differential input signal using an amplifier circuit, the amplifier circuit capable of amplifying input signals having a component that can extend to at least one power supply rail of the amplifier circuit, the method comprising:

• receiving the differential input signal at a first differential transistor pair and, in response, providing a differential first current to a cascode output stage of the amplifier circuit;
• generating a cascode control signal based on a magnitude of the differential input signal, wherein the cascode control signal is independent of a transconductance of the first differential transistor pair;
• providing the cascode control signal to each of multiple different transistors in the cascode output stage of the amplifier circuit, including an output cascode transistor coupled to an output node of the cascode output stage;
• and
• providing an output signal from the output node of the cascode output stage based on the magnitude of the differential first current and the cascode control signal.