The input stage comprises two differential transistor pairs, an NMOS pair and a
PMOS pair. The PMOS differential pair is active for most of the input common
mode range, and the NMOS is active for input voltages up to and including the
upper supply rail. The proprietary input stage minimizes the common-mode
voltage changes seen by the amplifier input stage for most of the input
common-mode range. This results in excellent disturbance rejection (high common
mode rejection, high power supply rejection and no cross over distortion) when
operating in this preferred common mode range (–VSY+1.5V to +VSY-1.5V).