Chip Design Of Signal Processing Of Automobile Wheel Speed Sensor In ABS

Automobile ABS(Anti-lock Braking System) is an indispensable security system with modern car in the world.The system can maintain directional stability and shorten the braking distance so that vehicles in the course of the entire braking,and effectively improve traffic safety,it has broad prospects with the car industry rapid development.As the most important dynamic parameters in this system - wheel speed signal measurement and treatment is especially important.Now the application of ABS system with domestic automobile is mainly dependent on imports,and most of domestic design treatments of the wheel speed signal are complex,high cost and poor anti-interference ability.The paper design a chip of signal processing of automobile wheel speed sensor in ABS based on Shanghai Belling 2um Bipolar technology in order to the wheel sensor signals generated by the characteristics.With the market,compared to existing similar products,the circuit structure is simple novel whose major functional modules includes oscillators,band-gap reference voltage source,multi-level zoom filter circuit,plastic compare current source circuit.The function of Signal processing circuit of the sensor is that irregular sinusoidal voltage signal is converted to the same frequency ideal square wave current signal,at the same time current duty cycle square wave signal should be appropriate(ideal for 50%), then followed up treatment by the counter.Using Cadence Spectre simulation tools for circuit design and simulation and using Virtuoso for drawing the layout of the territory. Because of the asymmetric bipolar,process of layout requires more rigorous and compact. In addition,EMI and the possible high-pressure situation become the focus of the design. Simulation results and chip test results show that the chip can be security with power supply voltage of 7V～15V.It's operating temperature environment is -50℃～150℃, pending the effective bandwidth of the signal is 1Hz～3KHz,the ideal output signal for the duty cycle is 7mA～14mA of the square wave current.Chip design has avoid the traditional circuit structure which is complicated and poor performance characters,in particular,to resolve that it cannot accurately deal with the problem of signal it the past because of wheel speed too high or too low.This design ensures that the chip can be still correct security operation,stable and reliable performance and low cost when the chip has great temperature character,wide supply voltage and many types of interference.Through parameters safety testing of the chip,result is showed that the design achieved the desired objectives to meet international standards of automotive electronics,and has very high practical value.