Patent ID: 7859340
Filing Date: 2010-12-28
Classification: H03F

Abstract:
1. An operational amplifier comprising: a ground rail; a first supply rail configured to connect to a first power supply providing a first supply voltage between the first supply rail and the ground rail; a second supply rail configured to connect to a second power supply providing a second supply voltage between the second supply rail and the ground rail, the second supply voltage being less than the first supply voltage; and a plurality of metal-oxide-semiconductor transistors fabricated to a reliability voltage limit less than the first supply voltage; wherein: the plurality of transistors comprises a first P-channel transistor, a second P-channel transistor, a third P-channel transistor, a fourth P-channel transistor, a first N-channel transistor, a second N-channel transistor, a third N-channel transistor, and a fourth N-channel transistor, each transistor of the plurality of transistors comprising a source, a drain and a gate; the source of the first P-channel transistor is coupled to the first supply rail, the drain of the first P-channel transistor is coupled to the source of the second P-channel transistor, the drain of the second P-channel transistor is coupled to the drain of the first N-channel transistor, the source of the first N-channel transistor is coupled to the drain of the second N-channel transistor, and the source of the second N-channel transistor is coupled to the ground rail; the source of the third P-channel transistor is coupled to the first supply rail, the drain of the third P-channel transistor is coupled to the source of the fourth P-channel transistor, the drain of the fourth P-channel transistor is coupled to the drain of the third N-channel transistor, the source of the third N-channel transistor is coupled to the drain of the fourth N-channel transistor, and the source of the fourth N-channel transistor is coupled to the ground rail; the gates of the second P-channel transistor, the fourth P-channel transistor, the first N-channel transistor, and the third N-channel transistor are coupled to the second supply rail.