High-input common-mode differential amplifiers

An operational amplifier, comprising:

• a level-shifting circuit to receive a first differential input and a second differential input of the operational amplifier, the level-shifting circuit including
• a first transistor and a second transistor to receive the first differential input,
• a third transistor and a fourth transistor to receive the second differential input, and
• output nodes to provide a level-shifted output based on the first differential input and the second differential input;
• and
• a differential circuit to receive the level-shifted output.

A method of using an operational amplifier, the method comprising:

• providing inputs to a level-shifting circuit of the operational amplifier;
• downshifting the common mode inputs to a numerical range to generate a downshifted output;
• and
• providing the downshifted output to a second phase of the operational amplifier to generate an operational amplifier output.

A memory device including an operational amplifier, the operational amplifier including

• a level-shifting circuit to receive a first common mode input and a second common mode input of the operational amplifier, the level-shifting circuit including
• a first n-type complementary metal-oxide-semiconductor (CMOS) transistor and a second n-type CMOS transistor to receive the first common mode input,
• a third n-type CMOS transistor and a fourth n-type CMOS transistor to receive the second common mode input, and
• output nodes to provide level-shifted outputs based on the first common mode input and the second common mode input, and
• a differential circuit to receive the level-shifted output.