Fully Differential Signal Conditioning Circuit for Current Excited Sensors

Abstract

The invention relates to the field of sensor detection, and in particular to a fully differential signal conditioning circuit for current excitation sensors, comprising a signal receiving unit, a programmable gain unit, an anti-aliasing filtering unit and an analog-to-digital conversion unit. All are connected in the above listed order. The signal receiving unit is used for receiving the signals outputted from the sensor, isolating DC components and outputting the signals. The programmable gain unit is used for outputting the AC signals outputted from the signal receiving unit as differential signals after being amplified or reduced. The anti-aliasing filtering unit is used for filtering high-frequency interference signals and outputting the signals as differential signals. The analog-to-digital conversion unit converts the received differential signals into digital signals before they are outputted. With a fully differential mode adopted in the whole signal flow of the invention, any part of the signal transmission path that is subject to noise interference can be effectively suppressed, and the immunity to external noise can be increased, thereby doubling the dynamic range and reducing even-order harmonic waves.

Description

technical field [0001] The invention relates to the field of sensor detection, in particular to a fully differential signal conditioning circuit applied to current excitation sensors. Background technique [0002] The sensor is a kind of precision sensing equipment widely used in various control fields. For example, in the aircraft field, due to the prominent failure of the main bearing of the aero-engine intermediary, which affects flight safety, it is necessary to have a high reliability and robustness, and in the field of Health management equipment that can accurately issue early warning signals within a sufficient lead time. [0003] At present, in the bearing fault diagnosis of some aeroengines, ICP or IEPE acceleration sensors are mostly used to detect the vibration signals of the bearings. Among them, the ICP sensor (integrated circuits piezoelectric) refers to the built-in piezoelectric sensor, which adopts modern integrated circuit technology. The charge amplifier...

AI Technical Summary

Problems solved by technology

[0004] No matter what kind of sensor is used, the electricity generated is very small, so the electrical signal generated by the sensor is easily disturbed by noise, and the signal transmission path is quite complicated. In addition to the oil film damping, the vibration signal of the intermediate bearing has to go through a long distance. The casing of the sensor is transmitted to the sensor, and the output signal of the sensor has to go through long-distance multi-path transmission to reach the collection receiver. The transmission process is accompanied by very strong interference, which makes the signal quality significantly reduced, and the useful bearing fault signal is often lost. Submerged in noise and other signals, it becomes a prominent difficulty in fault diagnosis

In order to improve the quality of the signal, it is necessary to effectively remove the noise interference. In the existing technology, the single-ended processing technology is generally used to process the signal output by the sensor. Since the single-ended processing technology cannot suppress the ground noise, the accumulated noise in the operational amplifier will be Degrades signal-to-noise ratio (SNR) performance, impacting system design

Even if a differential signal conditioning circuit built with dual op amps is used, the design becomes complicated due to the need for more resistive capacitor devices, and it is difficult to achieve complete balance due to the error of the external resistive capacitor device and the error inside the chip.

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