A simple and analytical design approach for input power matched CMOS RF LNA circuits and their scaling for lower power consumption, is introduced. In spite of the simplicity of our expressions, it gives excellent agreement with numerical simulation results using commercial CAD tools for several circuit examples performed at 2.4GHz using $0.18mu extrm{m}$ CMOS technology. These simple and analytical results are extremely useful in that they can provide enough insights not only for designing any CMOS LNA circuits, but also for characterizing and diagnosing them whether being prototyped or manufactured.