This paper presents a new transceiver for impulse radio ultra-wideband (IR-UWB) systems. This work is related to CHIST-ERA SMARTER project (Smart Multifunctional Architecture and Technology for Energy aware wireless sensoRs) which address autonomous wireless sensors nodes. The ultra low-power transceiver consists of an on-off keying (OOK) modulator/demodulator and a pulse generator. To reduce power consumption a solution based on clock gating technology has been implemented. The clock gating solution allowed us to divide by almost two the power consumption. A first prototype was developed on FPGA to prove the transceiver functionalities. The second prototype is an ASIC in ST Microelectronics 65nm CMOS technology designed using clock gating technology for ultra-low power purpose.