Apparatus and methods for amplifier input-overvoltage protection with low leakage current

A method of amplifier input-overvoltage protection with low leakage current, the method comprising:

• receiving a differential input signal between a first input terminal and a second input terminal of an amplifier;
• amplifying the differential input signal using a differential pair of input transistors of the amplifier, the differential pair of input transistors including a first input transistor and a second input transistor connected at a tail node;
• and
• protecting the differential pair of input transistors from overvoltage, including controlling an impedance between the first input terminal and a control input of the first input transistor using a first protection transistor, providing a bias voltage using a voltage source connected between the tail node and a control input of the first protection transistor, generating a bias current using a current source including a first terminal directly connected to the tail node, and providing clamping between the control input of the first input transistor and a control input of the second input transistor using a voltage clamp.