This　paper　presents　the　designs　of　the　monolithic　square　ring　resonators　based　on　the　composite　right/left-handed　(CRLH)　transmission　line　(TL)　operated　in　left-handed　slowwave　region.　The　proposed　resonator　is　fully　realized　by　only　using　CRLH　cells,　and　its　design　equation　is　derived　based　on　the　left-handed　guiding　properties,　indicating　how　the　frequency-dependent　slow-wave　factor　affecting　the　resonant　modes　inside　the　ring　resonator.　The　quality-factor　(Q-factor),　which　is　theoretically　extracted　from　the　complex　propagation　constant　of　the　proposed　CMOS　LH-TL,　exceeds　25　from　386　GHz　to　486　GHz.　Two　left-handed　(LH)　ring　resonators,　which　consist　of　eight　and　sixteen　unit　cells,　are　fabricated　in　the　standard　0.13　mu　m　1P8M　CMOS　foundry.　From　325　GHz　to　500　GHz,　the　on-wafer　measured　results　closely　agree　with　the　theoretical　predictions,　showing　that　the　8-cell　LH　resonator　has　two　resonating　frequencies　at　362　GHz　and　468　GHz　with　the　unload　Q-factors　of　14.2　and　21.2,　respectively.　The　16-cell　LH　resonator　has　Q-factors　of　17.6　and　22.3　at　the　resonating　frequencies　at　389　GHz　and　482　GHz.