This paper reviews recent progress in CMOS RF circuits with respect to technology scaling. It tunes out that RF transceivers almost ideally scale with technologies, even though some of RF circuits do not obey scaling law due to the noise, linearity, matching, and output power constraints. In order to overcome these constraints many design techniques including all digital approach, digital assisted approach, noise cancelling, non-linearity canceling, and RF filtering have been introduced. Also remaining challenges for the future is discussed.