This paper presents an ultra-wideband transceiver based on a newly proposed double thresholding scheme. The scheme does not require any precise synchronization and thus is practical in ad-hoc networks. The proposed architecture has high noise and multi-path fading signal immunities. All analog blocks are activated in a short period called 'flashing' to suppress total average power. A tested chip is manufactured using 0.15mum FD-SOI CMOS technology. The measured average power is 299muW at 25kbps data-rate over the distance of 35cm