Research And Design On LFMCW Radar Receiver Front_end

With domestic and foreign ship industry grown, the ship crash navigation requirements are also increasing. Combined domestic and foreign marine navigation radar, the system solutions of LFMCW shipborne navigation radar was proposed. LFMCW chirp signal can achieve very high frequency resolution, increase the effective bandwidth of the signal, and no blind spots from the other advantages, which have been widely used.Paper completed the LFMCW radar receiver front-end design and implementation scheme. In the system design would be carved frequency source module, microstrip filter module, LNA module, mixer module and balance amplifier module. Firstly, according to the design requirments for the overall index for the individual modules out followed by selecting the desired chip and used plate according to indicators drawn out of each module, followed by ADS software based noise figure of each module, linearity, gain, etc. arguments do link budget simulation, also made a receiver system frequency response characteristic simulation. For low-noise amplifier module, balanced amplifier module matching circuit simulation, stability and static operating point simulation results show that can meet the requirements of the required indicators. Microstrip filter module, first with ADS simulation two different styles of band-pass filter. During designing LNA module and balanced amplifier module circuit, we also need to pay attention to proper selection and placement choke inductor and filter capacitor near chip power PIN, capacitor closed chip using high Q blocking capacitor. In the actual circuit debugging flexibly debug their results matching circuit to make debugging and simulation results similar to the actual circuit. Mixer module uses a quadrature mixer, which 3dB bridge and splitters are designed according to the requirements of simulation obtained. The test results show that the index of each module can basically meet the requirements. Secondly, the paper LFMCW radar transmit signal problem has been described in detail, citing several leak cancellation method, described in detail the basic principles of leaks of cancellation, proposes a cancellation technical solution for analysis feasibility of eliminating the program, followed by a description of several couplers applied to the cancellation and design and simulation dual antennas used in this paper.The simulation results meet the requirements of pre-designed indicators. At the beginning of each module physical test results obtained were large different with pre-designed indicators. After check whether accidentally damaged chip when you are soldering and commissioning manual the resistors at the bias circuits and input and output matching circuit so that it can basically meet the design requirements.