This paper presents a CMOS fully differential folded cascode that operates at high frequency. Theoretical study on this amplifier is first presented and analyzed. The crucial parameters that may have influences on the trade-off for the design of this amplifier are also presented. Simulation results showing the characteristics of this amplifier are discussed. Using technology CMOS 0.18 μm with power supply equals to 3.3 V, this amplifier results a gain of 63.12 dB, a unity-gain bandwidth of 1.99 GHz, a phase margin of 56.9° and it consumes a total current of 1.15 mA.