Sensor anti-interference ability should be improved - News - Global IC Trade Starts Here Free Join

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

The sensor directly contacts or approaches the object to be measured to obtain information. Both the sensor and the measured object are in the disturbed environment at the same time, which is inevitably disturbed by the outside world. The anti-jamming measures taken by the sensor vary depending on the structure, type and characteristics of the sensor.
(1) Anti-jamming of the sensor for weak signal detection For the sensor with weak signal and high output impedance (such as piezoelectric, capacitive, etc.), the anti-interference problem is particularly prominent. The problems to be considered are:
(1) The sensor itself should take shielding measures to prevent electromagnetic interference. Also consider the effects of distributed capacitance.
(2) Since the output signal of the sensor is weak and the output impedance is high, the insulation problem of the sensor must be solved, and the insulation resistance of the printed circuit board must meet the requirements.
(3) The front circuit connected to the sensor must be compatible with the sensor, that is, the input impedance should be high enough and a low noise device should be selected.
(4) The transmission line of the signal needs to consider the attenuation of the signal and the influence of the distributed capacitance of the transmission cable. If necessary, drive shielding can be considered.
(B), the improvement of the sensor structure to improve the structure of the sensor, to a certain extent can avoid the introduction of interference, can have the following ways:
(1) The signal processing circuit is integrated with the sensitive components of the sensor, that is, integrated. In this way, the signal to be transmitted is enhanced, and the anti-interference ability is improved. At the same time, because it is integrated, it reduces the introduction of interference.
(2) The integrated sensor has the characteristics of compact structure and strong function, which is beneficial to improve anti-interference ability.
(3) Intelligent sensors can take anti-interference measures in software from various aspects, such as digital filtering, timing self-calibration, and feature compensation.
(3) Anti-common mode interference measures (1) For the sensor composed of sensitive components, in order to reduce the common mode interference caused by the power supply, positive and negative symmetrical power supply can be used to make the common mode interference voltage formed at the output end of the bridge. Close to 0.
(2) The measurement circuit uses a symmetrical circuit at the input end or a differential amplifier to improve the ability to suppress common mode interference.
(3) Use a reasonable grounding system to reduce the interference current formed by common mode interference into the measurement circuit.
(4) Anti-differential mode interference measures
(1) Reasonably design the sensor structure and adopt complete shielding measures to prevent external access and internal parasitic coupling interference.
(2) Signal transmission adopts anti-interference measures, such as twisted pair, shielded cable, signal line filtering, etc.
(3) Signal transmission using current or digital quantities.