Abstract: An operational amplifier includes a first differential input pair, a first switch and a second switch. The first differential input pair includes a first input transistor and a second input transistor. The first input transistor has a gate terminal coupled to an output terminal of the operational amplifier. The second input transistor has a gate terminal. The first switch is coupled between the gate terminal of the first input transistor and the gate terminal of the second input transistor. The second switch is coupled between a first input terminal of the operational amplifier and the gate terminal of the second input transistor.

Abstract: An undervoltage detection circuit includes a voltage divider, a voltage-to-current (V-to-I) converter and a current comparator. The voltage divider divides a supply voltage to generate a divided voltage. The V-to-I converter converts the divided voltage into a first current based on a first V-to-I transfer function, and converts the divided voltage into a second current based on a second V-to-I transfer function different from the first V-to-I transfer function. The current comparator compares the first and second currents to generate a comparison signal that indicates whether the supply voltage is sufficiently large.

Abstract: An operational amplifier includes a first differential input pair, a first switch and a second switch. The first differential input pair includes a first input transistor and a second input transistor. The first input transistor has a gate terminal coupled to an output terminal of the operational amplifier. The second input transistor has a gate terminal. The first switch is coupled between the gate terminal of the first input transistor and the gate terminal of the second input transistor. The second switch is coupled between a first input terminal of the operational amplifier and the gate terminal of the second input transistor.