A novel electronic PS pressure sensor 2

Figure 1 shows the cross-sectional structure of the PS pressure sensor, and Figure 2 shows the structure of its sensor section. As shown in the figure, there is a layer of diffusion resistor on the semiconductor silicon wafer of the pressure sensor. If pressure is applied to this resistor, its resistance value will change due to the piezoelectric resistance effect. The part that is subject to strain, namely the diaphragm, becomes thinner due to its susceptibility to pressure. In order to alleviate the influence of stress from the sensor base, the pressure sensor is installed on a glass base. When a certain pressure is applied to the cavity, the diaphragmdiode undergoes a certain degree of stretching or contraction, resulting in deformation. The arrangement method of piezoelectric resistors is shown in Figure 3, where the resistance values of resistors R2 and R4 under tension increase; The resistance values of the compressed resistors R1 and R3 decrease. Due to the bridge structure composed of various piezoelectric resistors as shown in Figure 4, if they are connected to a constant current source, the output voltage Δ V will be obtained at the output terminal due to the increase or decrease of pressure. The magnitude of Δ V is determined by the following equation: In equation (1),diode when the pressure is zero, Δ V is equal to the bias voltage Voffset. In an ideal state, we hope Voffset=0V. In fact, when generating a diffusion resistor, there is always a certain voltage value due to the differences in the size and impurity concentration of the formed diffusion resistor. When the pressure is zero, R1=R2=R3=R4=R， We denote the change in resistance of R1 and R2 when a certain pressure is applied as Δ R; The corresponding changes in resistance of R3 and R4 are denoted as - Δ R, so equation (1) is simplified as followsdiode