Junction isolation is promising for cost reduction and high power circuit applications due to its relatively lower fabrication complexity and thermal conductivity, but larger area and collector-substrate capacitance (C-cs) seem drawbacks as compared to the deep trench isolation (DTI) technology. A simulation work is proposed for the size selection guide of unit cell to have the low cost benefit of junction isolation without sacrificing the gain and noise performance of the low noise amplifier (LNA) operated at 5.2 GHz. (C) 2003 Elsevier B.V. All rights reserved.