Research And Design Of Wide-bandwidth Linear Hall Sensor

Hall sensor is the most widely used and lowest cost sensor design of the magnetic sensors.It has high isolation,high stability and strong endurance,and be suitable for further circuit designs and productions,such as sensing detection,distance measurement,position tracking.The mainstream research direction of hall sensor focus on the design of high precision,high power and wide bandwidth.As the new research hotspot,high-bandwidth linear hall sensing has attracted the attention of scientific researchers in the field of sensors in China and abroad.Nowadays,researchers have mature technologies and design schemes.Including widebandwidth fast sensing,hall sensor also has to contain the performance of high linearity,low offset,and low noise.Based on the theoretical analysis of the hall element,the use of dynamic offset voltage elimination technology and temperature compensation technology,this paper proposes a linear Hall sensor circuit design with wide bandwidth characteristics under the 0.18?m Semiconductor process,we show the specific research work as follows:1.The paper proposes a hall sensor signal path with low offset voltage.The main signal path is based on two dynamic offset voltage technologies: the current rotation and the chopping modulation.The first one eliminates the offset voltage generated by the Hall element,the else eliminates the offset voltage generated by the internal operational amplifier.2.The paper proposes a current feedback instrumentation amplifier.The feedback mode of this instrumentation amplifier is the indirect current feedback.This amplifier includes differential and common mode current feedback transconductance.The differential mode current feedback transconductance reduces the offset voltage of the differential output caused by the mismatch of the input mosfet.The common one suppresses the static operating voltage drift of the entire instrumentation amplifier.3.The paper proposes a hall sensing module with low temperature drift.The structure uses the resistance compensation technology and the current compensation technology.In the case of not using the resistance with temperature coefficient,the design has two first-order temperature coefficient compensation variables introduced into the Hall sensing module.The temperature drift of the Hall element can be accurately compensated according to environmental changes.4.The paper proposes a output low-pass filter with driving capability.This structure can cope with the load change in the outside design,and swallow the source and sink current in a rational range.Couting with the load capacitance of the entire chip,the whole output filter can be seen as a second-order low-pass filter,which increases the slope of the filter edge,so that the offset voltage and noise generated by the main path are filtered out of the chopping frequency.The wide-bandwidth linear hall sensor design can work normally in 5V-12 V,and the bandwidth of main signal path is 100 k Hz.The entire design equivalent input noise is 124.221 n V/(Hz)^1/2 at the thermal noise frequency,with the common-mode rejection ratio CMRR is133.507 d B.This paper uses the Cadence to conduct circuit design,simulation verification and layout design.Finally,the results of the tape-out shows the chip can work normally,and all the indicators of work meets the requirements.