| In recent years, the wireless communication has become the key technology of a variety of medical and non-medical applications. But the power of most wireless communication equipments is supplied by batteries, and this puts forward restrict requirements on the power consumption of the system. Low-frequency awaken technology can effectively reduce the power consumption of the system and extend the service life of the battery. The analog modem, as an indispensable part in the low frequency awaken system, has attracted more and more attention.Based on the application of wireless medical monitoring system, the low power consumption principle of the module of low frequency awaken and the circuit implementation of the analog modem has been studied. The main research is as follows:(1) A suitable analog modem system for amplitude shift keying(ASK) modulation has been builded. It can minimize the influence on the demodulation results of the out-of-band noise without any increase in the power consumption of the system, improve the system sensitivity, so as to ensure the correctness of the demodulation.(2) The circuit of the analog modem has been designed. All the circuit modules use the threshold circuit design method, most of the transistors are operating in the threshold region, so as to reduce the power consumption of the system.(3) The analog modem system layout design and the back-end simulation.This design is based on the SMIC 0.18 um technology. The simulation results show that the analog modem system can correctly demodulate the ASK modulation signal which is transmitted to the antenna under the SS/TT/FF process Angle.The range of the working temperature is-40-120 ? and that of the power supply voltage is 2.0-3.6 V. The detection sensitivity of the system can reach 1 mVPP. The power consumption of the system is lower than 3.3 uA under typical working conditions(power supply voltage is 3.3 V and the working temperature is 27 ?). |
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