This paper describes a backward-compatible 60/5 GHz wireless local (or personal) area network system, with emphasis on the low-cost, multi-function, 0.25 um 1P5M CMOS (complementary metal oxide semiconductor) development of the RF SOC
(radio-frequency system-on-chip), in support of making smart antenna array at 60 GHz and MIMO (multiple inputs and multiple outputs) system at 5 GHz employing OFDM (orthogonal frequency division multiplexing). Methods of implementing two important building blocks for the RF SOC using transmission lines approach at the two extreme spectra are presented. Results show that an eight-element (two-by-four) CMOS antenna array produces a gain of 5.24 dBi at 60 GHz and an active synthetic transmission line exhibits 0 dB loss at the 5 GHz ISM bands. Following the measured results for the synthetic, quasi-TEM transmission lines, we conclude that a complete RF SOC for the 60/5 GHz wireless system is feasible in the near future.