In this paper a low-voltage two-stage Op Amp is presented. The Op Amp features rail-to-rail operation and has an input stage with a constant transconductance (gm) over the entire common-mode input range. The input stage consists of an n-and a p-MOS differential pair connected in parallel. The constant gm is accomplished by regulating the tail-currents with the aid of an MOS translinear (MTL) circuit. The resulting gm is constant within 5%. The common-source output range employs a feedback circuit which also contains an MTL circuit. This feedback circuit ensures class AB operation and prevents the transistors in the output stage from cutting off. The Op Amp will be realized in a semi custom CMOS process with minimum channel lengths of 10μm. Simulations show that the minimum supply voltage is less than 2.5 V. A unity gain bandwidth of 550kHz and a DC voltage gain larger than 80 dB are feasible. The input range exceeds the supply rails, whereas the output range reaches the rails within 130 m V.