This paper presents a low-power coherent receiver for UWB pulsed Radar for motion detection. Due to accuracy of the radar motion detection, coherent detection scheme is adopted in the receiver. To relax the stringent requirement of timing synchronization, sliding correlation detection is proposed. The clocking step which determines detection resolution is determined by 2ns which is half of a pulse width or equivalent to 30cm. Receiver is designed in 0.13-mu m CMOS process from 1.5 V supply. The pulse center frequency is 4GHz. The receiver includes a high voltage gain LNA, a analog correlator, a sampling comparator and a Flip Flop. The whole receiver excluding an LNA consumes 0.9 mA of DC current and 10pJ/pulse at the pulse rate of 16MHz. The active size is 600 x 380 mu m(2).