The power management technique is employed in the direct down-conversion non-quadrature microwave Doppler radar transceiver for the non-contact vital sign detection based on 0.18 µm CMOS technology. The overshoot and undershoot types of the transient waveform distortion and the simultaneous switching noise (SSN) caused by the high speed pulse signal will severely influence the accuracy for the vital sign detection, so that this investigation clearly analyzes the pulse period, pulse width, rise/fall times and the voltage levels of the pulse bias. In the circuit design, the low power current-reused (CRU) power amplifier (PA) can maintain enough output power by using the crucial double primary transformer (DPTF) and balun. The presented LNA with a differential inductor can provide the noise matching needed and increase the transducer gain in order to achieve the optimal power consumption and the transducer gain in the Rx mode. The excellent isolation between the Tx and Rx mode is obtained with the new parallel directed switch. The overall power consumption of the presented transceiver with the optimal pulse bias is 60% lower than the conventional transceiver with the direct current (DC) bias, and the null detection point and DC offset can be eliminated by the tunable phase shifter.