Car Crash Millimeter-wave Fmcw Radar Front-end Integration Of Key Technologies

Sheng Huaimao (microelectronics and solid-state electronics) Directed by Prof, Xia Guanqun and Sun XiaoweiAutomotive anti-collision millimeter-wave radar system is widely used in automotive application in recent years. High stability and small size is necessary for automotive radar system. So the thesis is focused on integration of millimeter-wave radar front-end.First of all, single port negative impedance oscillator is analyzed in the thesis. A design method of Gunn diode VCO is introduced and an VCO chip using Gunn diode is fabricated. The substrate of the VCO chip is GaAs with dimension of 4.4mmx3.9mm. The center frequency of the VCO is 28.8GHz and the band width is about 20 MHz. The measured result is far from what is want. The causation is analyzed.Compared with Gunn diode, MESFET has the advantage of high efficiency, flexible design and easy to integrate. The two ports negative resistance oscillating network is analyzed and an extremum-line model of microwave transistor oscillating network output impedance is developed. It simplifies the optimization of feedback components and accelerates the design of negative impedance oscillator. A 14GHz MESFET VCO is designed and simulated with HP ADS. The size of the circuit is about 3.4cmx3.9cm. The center frequency of the VCO is 14.14GHz with band width of more than 100MHz. The output power is 2~6mW. The dependence of band width on the circuit configuration is discussed here. It is a pity that the phase noise is not measured because no suitable instrument is available.A power circuit is designed for MESFET VCO circuit with DC +5V output and adjustable negative voltage output. The character of the circuit is that the negative output is turn on earlier than the DC +5V output when power on and is turn off later than the DC +5V output when power off.The character of radar system is restricted by parasitical AM. To restrain parasitical AM, a low pass filter is used in the IF circuit. The result shows that theFMCWdetecting range of the radar with the filter is greater than that without.In the last part of the thesis a scheme for integration of millimeter-wave radar front-end is put foreword.