Signal processing circuit of linear Hall sensor

Abstract

The invention discloses a signal processing circuit of a linear Hall sensor, which comprises an over-sampling loop and two chopping modulators. The over-sampling loop consists of a CPA (chopping amplifier), a first order loop wave filter, a four-bit digital converter and a feedback circuit, wherein the first order loop filter contains a filter capacitor and an integrating amplifier (ITA). The two chopping modulators are respectively embedded in front of and behind the CPA. The CPA is an operational transconductance amplifier which linearly converts an outputted voltage signal into current and keeps fixed gain under the full conditions. The filter capacitor and the ITA are connected with an active first order wave filter of the over-sampling loop. The four-bit digital converter converts a filtered signal into a four-bit digital signal; and the feedback formed by a four-bit DAC (Digital-to-Analog Converter) and a Hall dish converts an output code into feedback voltage; and the feedback voltage is subtracted from an inputted signal. As the inputted signal is very weak, the offset voltage of the CPA and the flicker noise are modulated by the chopping modulators in front of and behind the CPA into a high-frequency band and are filtered by a wave filter. The constant Gm in the CPA keeps the loop more stable under the full conditions.

Description

technical field [0001] The invention relates to a signal processing circuit, in particular to a signal processing circuit of a linear Hall sensor. Background technique [0002] The linear Hall sensor senses the magnetic field and converts the change of the magnetic flux passing through the sensor into an electrical signal. In the past, people usually directly amplify the Hall induced electromotive force through an amplifier to control other systems. At present, in the face of lower cost and higher efficiency requirements, Hall disks are directly embedded in CMOS technology and SOC systems (system on chip systems on chips) are used. Hall effect devices in CMOS technology are capable of sensing magnetic fields, but with very low sensitivity. For the requirement of high linearity, it is not suitable to directly amplify the Hall induced electromotive force. Built-in oversampling ADC is a common design at present. [0003] In the control system, the Hall sensor is required to ...

AI Technical Summary

Problems solved by technology

[0004] In existing inventions, conventional designs usually use discrete oversampling ADCs, or second-order or even higher-order oversampling ADCs. These structures are not only complex in design but also require a larger layout area

Conventional designs usually face severe noise problems in feedback, and for more complex designs and more layout overhead for filters, these will lead to deterioration of linearity

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