A high gain cascode low noise amplifier (LNA) for 5G communication band of 22~4 GHz was designed and implemented in a 025 μm GaAs pHEMT process. By combining the parallel RC feedback with the common gate grounding capacitor, the LNA with broadband and high gain was completed without the use of source inductance. The measurement results showed that the gain of 22~4 GHz band was better than 24 dB, the output third-order intermodulation (OIP3) was 28 dBm, the noise figure (NF) was less than 078 dB, the power consumption was 190 mW, and the chip area was (810×710) μm2. The Figure of Merit (FOM) was 144 dB, which had certain advantages compared with relevant LNAs.