Design Of An Up-conversion Mixer For The Low-IF Continuous-wave Radar In The W-Band

Recently,millimeter-wave non-contact detection radar has been playing an important role in vibration measurement,especially for vital sign detection.The Doppler radar technology,based on the nonlinear Doppler phase modulation effect,has become a topic of concern.In this paper,a W-band Doppler radar,using a low-IF quadrature architecture,has unique advantages in detection accuracy.And a complex signal demodulation technique is proposed to reconstruct the motion information.This paper focuses on the design of an up-conversion mixer for the Doppler radar.This up-conversion mixer is mainly composed of mixer core,single to dual converter,output buffer and matching networks.According to the system requirements and the characteristics.of typical mixers,the double balanced Gilbert cell is preferred.Also,the pseudo-differential trans-conductance stage and the transformer load stage are utilized to meet the limitation of low supply voltage;Considering the differential inputs of double balanced mixer,a single to dual converter(SDC)is needed.To provide enough power to drive next stage,a output buffer is necessary.A capacitance neutralization technique is applied to compensate the miller effect and improve the stability;To reduce transmission loss of high-frequency signal,three matching networks are designed and implemented by transformers.Finally,the points of the layout design are analyzed and the simulation results are obtained.In this paper,TSMC 65nm CMOS technology is used to complete the overall circuits,and the area is 0.624mm X 0.602mm.The low-IF frequency of this mixer is 10kHz?100kHz and the LO frequency is 105GHz.The post-simulation results show that this mixer has a conversion gain greater than 1dB and an OP1dB greater than-9dBm.The measured LO-RF isolation is better than 35 dB.Moreover,the overall power consumption is less than 20mW.In conclusion,the simulation results completely meet the system requirements and this up-conversion mixer is able to be applied to Low-IF Continuous-wave Radar in the W-Band.