Self-protected high-transconductance input stage for comparators and amplifiers

A system comprising:

• a first portion of a transconductance circuit including:
• a first degeneration transistor coupled to a first protection device;
• a first input transistor configured to receive a first portion of a differential input signal at a first input node and, in response, provide a first output current at a first output node, wherein a gate terminal of the first input transistor is coupled to a gate terminal of the first degeneration transistor;
• and
• a first bias circuit configured to provide a bias signal to the first protection device;
• and
• a second portion of the transconductance circuit including:
• a second degeneration transistor coupled to a second protection device, wherein the second protection device is coupled to the first protection device;
• a second input transistor configured to receive a second portion of the differential input signal at a second input node and, in response, provide a second output current at a second output node, wherein a gate terminal of the second input transistor is coupled to a gate terminal of the second degeneration transistor;
• and
• a second bias circuit configured to provide a second bias signal to the second protection device.

A method for controlling gain and bandwidth characteristics of an input stage circuit, the method comprising:

• receiving first and second input stage input signals at respective first and second input nodes of respective first and second input transistors;
• receiving the first and second input stage input signals at respective first and second input nodes of respective first and second degeneration transistors;
• using a first bias circuit, providing a first bias signal to a gate terminal of a first protection device;
• using a second bias circuit, providing a second bias signal to a gate terminal of a second protection device;
• in response to receiving the input signals at the first and second degeneration transistors, adjusting an impedance characteristic of a signal path coupling the first and second input transistors;
• providing a first input stage output signal using a first output terminal of the first protection device, wherein the first protection device is provided in cascode with the first input transistor;
• and
• providing a second input stage output signal using a second output terminal of the second protection device, wherein the second protection device is provided in cascode with the second input transistor.