Design Of Broadband Miniaturized Wireless Transceiver System

Whether in civil or military areas,the research and application of Doppler velocity measurement system have been very extensive.In the civilian areas it can monitor the speed of vehicles to avoid the occurrence of traffic accidents.It can guide the safe landing of civil aviation aircraft to ensure the safety of passengers.In the military field it can monitor the speed of the enemy aircraft to provide timely warning.This system can also be used for weapons guidance to let the target be accurately destoried.With the advancement of science and technology,modern communication system has been development rapidly.More and more areas need wireless communications.So the existing frequency of resources has become increasingly urgent.And the RF channel become more and more precious.Under the condition of communication frequency can not be largescale expansion,how to effectively use the existing RF channel has become an important issue.Therefore,the development of broadband miniaturized wireless transceiver system is of great significance.This paper studies a broadband miniaturized wireless transceiver system with twice frequency conversion.This system's characteristics are small steps,large dynamic range and so on.Its receiver input frequency covers 2GHz~3GHz,and the output center frequency is 140 MHz.The transmitter input frequency is 140 MHz,and the output frequency covers 2GHz~3GHz.In order to effectively suppressing the mirror frequency and ensuring the purity of the output signal,this paper uses two frequency conversion structure.And through the design of low noise amplifier,the system ensures the overall noise standards.One of the difficulties of this article is to achieve a small step of 0.0001 Hz.After comparing the various small steps,we improved the existing scheme of miniaturization,and finally realized the function by using "phase-locked loop + direct digital synthesizer + divider".In addition,the receiving dynamic range is another difficulty in this paper.We use cascaded automatic gain amplifier to achieve this goal.And we solve the problem that the cascaded automatic gain amplifier often can not be locked by changing the way of traditional feedback.