This paper presents an ultra wideband track and hold (T/H) circuit using direct RF subsampling for radar applications. The circuit enables digitization of the whole received UWB pulse instead of a sole distance measurement used in correlating receivers. In this way, more target information is acquired for further digital processing. Subsampling was applied to achieve a low power concumption of 1.4 mW which includes the T/H core and clock generator. The circuit operates on a rail-to-rail input using the bootstrapping technique. To avoid reliability issues caused by bootstrapping the sampling switch, bulk switching and precharge techniques are introduced. An effective resolution bandwidth of 5.5-GHz was measured with an accuracy of 6-b. The track and hold circuit has been implemented in 40 nm CMOS.