A low voltage op-amp with constant-Gm rail-to-rail input and high swing self-biasing super cascode output stage

Probably the most important building block in a mixed-signal system is the operational amplifier. Power consumption is a critical performance characteristic in fast op-amp designs. Low power supplies have become dominant in modern mixed-signal VLSI systems. Unlike CMOS digital modules, which are functionally insensitive to power supply variations, traditional analog cells not only fail to achieve the expected performance characteristics but may also become totally inoperative. This fact, together with the requirement of high density mixed analog-digital VLSI systems, urges the research of new analog architectures capable of achieving high performance characteristics in exceedingly noisy environments, where the presence of digital circuitry is abandoned. Therefore, power supply insensitive, self-biasing architectures are highly advantageous, successfully limiting the design, layout and routing effort and guaranteeing the product success