Structure and working principle of diffused silicon pressure transmitter

- Jul 22, 2020-

Structure composition of diffused silicon pressure transmitter

Since the output of the pressure sensor UPX19 is a non-standard signal, in practical applications, in order to make the sensor universal and facilitate signal transmission and recording, the sensor is used in conjunction with a standard signal input circuit to output a standard signal. The sensor that outputs the standard signal at this time is called the pressure transmitter UPB13.

In short, the transmitter is gradually developed from the sensor. The diffused silicon pressure transmitter studied in this paper is mainly composed of MEMS sensor, measuring capsule, interface and processing circuit (smart circuit board).

The pressure sensor and the diode temperature sensor are packaged on the top of the measuring capsule, and the capsule body is clamped by two sealing flanges to form the measuring part of the transmitter, which is responsible for converting the pressure signal to be measured at the work site into a voltage signal. In addition, an electronic circuit board, a liquid crystal display header and a connection terminal constitute the display part, which is responsible for converting the voltage signal output by the sensor to 4-20mA through amplification,then outputting a standard current signal.

Working principle of diffused silicon pressure transmitter

Based on the piezoresistive effect of monocrystalline silicon, an elastic component is fabricated in a certain direction on the silicon wafer with advanced micro-electromechanical processing technology, and four force-sensitive resistors with equal resistance are fabricated by integrated circuit technology at the proper position, which connects to a Wheatstone bridge. A constant voltage (current) is applied to the bridge, and the measured pressure is transmitted to the silicon chip through the silicone oil sealed in the measuring capsule without loss, then the transmitter outputs a voltage signal linearly proportional to the pressure to be measured, and then the voltage signal is amplified and converted into a two-wire standard signal through electronic circuits.

To sum up:

It can be known from its working principle that the pressure sensor is an important part of the pressure transmitter UPB1, and the main source of temperature drift of the transmitter is the temperature drift of the silicon pressure sensor. The current research on temperature drift compensation of silicon pressure transmitters is also mainly focused on the part of silicon pressure sensors.

For details, please contact Qi Huang