Detection circuit of bridge sensor, chip and detection system

A chip, comprising a detection circuit of a bridge sensor, wherein, the detection circuit of the bridge sensor, comprises:

• an alternating current excitation module, and
• a signal conditioning module, an analog-to-digital conversion module and a processing module connected in sequence;
• wherein
• the alternating current excitation module is configured to apply an alternating current excitation signal to the bridge sensor;
• the signal conditioning module and the analog-to-digital conversion module are configured to sequentially process an output signal from the bridge sensor;
• and
• the processing module is configured to demodulate a processed output signal, and obtain a detection information of the bridge sensor according to a demodulated output signal;
• wherein the signal conditioning module comprises an instrumentation amplifier and an anti-alias filter;
• a first input terminal of the instrumentation amplifier is connected to an output terminal of the bridge sensor, an output terminal of the instrumentation amplifier is connected to an input terminal of the anti-alias filter, and an output terminal of the anti-alias filter is connected to an input terminal of the analog-to-digital conversion module;
• and
• the signal conditioning module further comprises a cancellation circuit;
• wherein the instrumentation amplifier has two second input terminals, and the cancellation circuit comprises:
• a first direct current source,
• a second direct current source,
• a third switch configured to switch the first direct current source or the second direct current source to one of the second input terminals, and
• a fourth switch configured to switch the first direct current source or the second direct current source to the other one of the second input terminals;
• wherein the processing module is further configured to control the third switch and the fourth switch to execute a switching operation;
• and
• a current output from the first direct current source and a current output from the second direct current source are equal in magnitude and opposite in direction;
• the cancellation circuit is configured such that a magnitude of a voltage output from the instrumentation amplifier meets a preset requirement in the case when no external force acts on the bridge sensor;
• and
• wherein the preset requirement comprises:
• a difference between the magnitude of the voltage output from the instrumentation amplifier and a magnitude of a reference voltage input to the instrumentation amplifier is zero, and the reference voltage is a common mode voltage provided by the analog-to-digital conversion module.

A detection system, comprising a bridge sensor and a detection circuit of a bridge sensor, wherein, the detection circuit of the bridge sensor comprises:

• an alternating current excitation module, and
• a signal conditioning module, an analog-to-digital conversion module and a processing module connected in sequence;
• wherein
• the alternating current excitation module is configured to apply an alternating current excitation signal to the bridge sensor;
• the signal conditioning module and the analog-to-digital conversion module are configured to sequentially process an output signal from the bridge sensor;
• and
• the processing module is configured to demodulate a processed output signal, and obtain a detection information of the bridge sensor according to a demodulated output signal;
• wherein the signal conditioning module comprises an instrumentation amplifier and an anti-alias filter;
• a first input terminal of the instrumentation amplifier is connected to an output terminal of the bridge sensor, an output terminal of the instrumentation amplifier is connected to an input terminal of the anti-alias filter, and an output terminal of the anti-alias filter is connected to an input terminal of the analog-to-digital conversion module;
• and
• the signal conditioning module further comprises a cancellation circuit;
• wherein the instrumentation amplifier has two second input terminals, and the cancellation circuit comprises:
• a first direct current source,
• a second direct current source,
• a third switch configured to switch the first direct current source or the second direct current source to one of the second input terminals, and
• a fourth switch configured to switch the first direct current source or the second direct current source to the other one of the second input terminals;
• wherein the processing module is further configured to control the third switch and the fourth switch to execute a switching operation;
• and
• a current output from the first direct current source and a current output from the second direct current source are equal in magnitude and opposite in direction;
• the cancellation circuit is configured such that a magnitude of a voltage output from the instrumentation amplifier meets a preset requirement in the case when no external force acts on the bridge sensor;
• and
• wherein the preset requirement comprises:
• a difference between the magnitude of the voltage output from the instrumentation amplifier and a magnitude of a reference voltage input to the instrumentation amplifier is zero, and the reference voltage is a common mode voltage provided by the analog-to-digital conversion module.