Pseudo-differential DISTRIBUTED AMPLIFIER (PD(DA)) is an effective method in increasing the bandwidth of a broadband AMPLIFIER. This study investigates different methods with same power consumption and chip area for enhancement gain-bandwidth in a cascaded pseudo differential DISTRIBUTED AMPLIFIER (CPD(DA)) and compare them. The choice of optimal design depends on the gmRo parameter of the P(DA) cells. The proposed circuits have been implemented in 0. 18-μ m RF-CMOS technology. The simulation results show that in this technology, in order to obtain a 0-40GHz bandwidth that requires low gmof the P(DA)'s cell-transistor, two cascaded PD(DA) with three stages has a better performance than a three cascaded PD(DA) with two stages. In two cascaded PD(DA) with three stages structure, a gain of 10dB can be achieved in the bandwidth of 40GHz in 0. 18-μ m RF-CMOS technology. In this AMPLIFIER, parameters S11, S22, S12, are-12,-10, and-16 dB, respectively and noise figure is equal to 4. 6 and P1dB is +3. 5dBm. This AMPLIFIER has 230mW power consumption and a chip area of 0. 63 mm2. These values show the good performance of the proposed AMPLIFIER, compared to the results of previous works on similar AMPLIFIERs.