| As a significant part of vehicle driving safety, Advanced Front-lighting System(AFS)is a system which can provide optimum lighting by adjusting the car's front-light in different driving situation. Angle sensor is an important part of AFS for the car's driving situation detection.This work is focused on two parts of electromagnetic coupled angle-sensor in AFS:sensor structure and corresponding signal processing circuit. In the respect of sensor structure design, the sensor structure's model of electromagnetic coupled angle-sensor is established and analyzed, and the detail design method of the coil structure is summarized. Based on the Finite Difference Time-Domain(FDTD) method and electromagnetic field principle,the functions between coupled signals on receiving-coils and rotation angle of feedback-coil are obtained. The validity of the functions is verified by Advanced Design System(ADS)and the coil structure is implemented by PCB. In the respect of signal processing circuit design, the circuit of sample&hold pulse generator is designed, which replaces the integrator.It generates the pulse by digital counter using the clock from LC synchronizing oscillating signal and the clock from high-frequency ring-oscillator circuit, which decreases the area and power dissipation. The solutions of harmonic suppression and signal stability on LC oscillator is optimized. The following modules are designed, including a rail-to-rail VGA,RC low-pass filter signaling pathway, current bandgap, low dropout regulator(LDO) voltage converter, ADC connection and IIC connection, which improves the integrity of this angle-sensor system. Then the decoded-angle and the pulse width modulated(PWM) wave are output, which is utilized to control the car's front-lighting.The layout design, simulation and tape-out about this angle-sensor chip are done by Global Foundry 0.35?m. The results show that the harmonic wave and bias point of LC oscillator is worked out. Sample&hold pulse is done, its precision is analyzed and optimization plan is provided. Meantime, debugging and decoding of digital circuit works fine.The precision can reach 0.05?. |
PDF Full Text Request