Good sensor design is the result of experience plus technology. It is generally understood that a sensor converts a physical quantity through a circuit into a description of a physical quantity that can be expressed intuitively in another way. For example, a signal is converted to a higher voltage and current that only depends on the physical measurement, and then displayed. Therefore, a few points should be noted:

1. Generally, the measured physical quantity is very small, and there is usually conversion noise inherent as the physical conversion element of the sensor. For example, when the signal strength of the sensor is 0.1~1uV at a magnification of 1, the background noise signal has such a large level that it is even annihilated. How to take out the useful signal as far as possible and reduce the noise is the primary problem to be solved in sensor design.

2. The sensor circuit must be simple and refined. Consider a 3-stage amplifier circuit with a 2-stage apF amplifier circuit, which amplifies the signal and the noise at the same time. If the noise is not significantly deviated from the useful signal spectrum, no matter how the filtering is used to amplify both, the SNR will not be improved. Therefore, the sensor circuit must be refined and simple. If you can save one resistor or capacitor, be sure to remove it. This is a problem that many engineers who design sensors tend to overlook. It is known that the sensor circuit becomes more and more complicated with the noise problem, and becomes a strange circle.

3. Power consumption. The sensor is usually at the front end of the subsequent circuit and may require a longer lead connection. When the power consumption of the sensor is high, the connection of lead will introduce some meaningless noise and power noise, making the subsequent circuit design more difficult. How to reduce the power consumption in the case of sufficient is also a big test.

4. Selection of components and power supply circuit. The choice of components must be enough to use it, as long as the device indicators in the required range can be, the rest is circuit design issues. The power supply is a problem that the sensor circuit design process must meet, do not pursue the power index that cannot be reached, but choose an op amp with a better common mode rejection ratio, using differential amplifier circuit design may be the most common switching power supply and devices can meet your requirements. The uncoupling of the power supply must be designed reliably and in accordance with the requirements of the device manual.