For the disadvantages of the complementary metal oxide semiconductor (CMOS) technology under high frequency, a wideband low noise amplifier (WLNA) for wireless telecommunication systems is designed based on gallium arsenide pseudo high electron mobility transistor (GaAs pHEMT). Negative feedback is used to design the WLNA to obtain smooth gain, low input and output reflection coefficient. Simulations were conducted with Advanced Design System 2005 for the designed circuit. Simulation results show that, in the band of 0.3～2.2 GHz, the gain of this WLNA is below 12 dB and fluctuation of gain is under 3 dB, while for the noise figure being between 1.04 dB and 1.43 dB, the input and output reflection coefficients are both below -10 dB, and the group delay in the whole band is close to linearity and this WLNA is unconditionally stable. This WLNA can well meet actual demands.