A novel direct-conversion structure for non-contact vital sign detection system

In this paper, an analysis on non-contact vital sign detection system is presented. It is concluded that the null point and dc-offset are related, so that the associated problems can be solved. Based on this principle, a novel structure of direct-conversion transceiver, which contains a tuneable phase shifter, is proposed to achieve a better performance. Two sets of simulations are employed to demonstrate the new structure. With this structure, dc-offset and null point can be eliminated and it is very easy to reach the optimal detection.