ABSTRACT
Operational amplifier is a basic unit in the circuit, which is widely used in power management chip, media player, mobile handheld device and vehicle navigation system. Today, the MOS tube feature size continues to decrease, the power supply voltage is also becoming small (Mahmoud S.A. et al. 2000). The resulting problem is that the operating range of the operational amplifier is affected, because the threshold voltage of the MOS transistor is not reduced (Khare K. et al. 2008). In some applications, operational amplifiers require a wide range of common mode input voltage. So it is very important to design a low voltage and high gain rail to rail operational amplifier.
