1. Generally, the measured physical quantity is very small, and usually also has the inherent conversion noise as the physical conversion element of the sensor. For example, the signal strength of the sensor under the magnification of 1 is 0.1~1uV, and the background noise signal at this time is also so large that it is even annihilated. How to extract useful signals as much as possible and reduce noise is the primary problem of sensor design.
2. The sensor circuit must be simple and refined.Suppose an amplification circuit with a 3-stage amplifier circuit and a 2-stage active filter amplifies the signal and also amplifies the noise. If the noise does not deviate significantly from the useful signal spectrum, no matter how the filter is filtered, the two are amplified at the same time. The signal-to-noise ratio is not improved.Therefore, the sensor circuit must be refined and simple. To save a resistor or capacitor, it must be removed. This is an issue that many engineers designing sensors tend to overlook. It is known that the sensor circuit is plagued by noise problems, and the more the circuit is modified, the more complex it becomes, which becomes a strange circle.
3. Power consumption problem. Sensors are usually at the front end of subsequent circuits and may require longer lead connections.When the power consumption of the sensor is large, the connection of the lead wire will introduce all the unnecessary noise and power supply noise, making the subsequent circuit design more and more difficult. How to reduce the power consumption when it is enough is also a big test.
4. Selection of components and power circuit.The selection of components must be sufficient, as long as the device indicators are within the required range, the rest is the problem of circuit design.The power supply is a problem that must be encountered in the design process of the sensor circuit. Do not pursue unattainable power supply indicators, but choose an op amp with a better common mode rejection ratio, and use a differential amplifier circuit to design the most common switching power supply and device can meet your requirements.
Post time: Jun-20-2022