1. Description

Low temperature pressure sensor compensation circuit

Figure 1 typical compensation circuit in a low temperature coefficient resistance network.

2。 Temperature compensation principle of passive resistance

2.1。 Bias voltage and bias temperature coefficient compensation

Expression of temperature coefficient α R gives:

Ar = RT − r zero × One t − t zero

(V)

Figure 2 illustrates the resistance G series configuration with a near zero resistance temperature coefficient. Temperature coefficient T for G and R α R G, as in equation (6). The comparison of equations (5) and (6) shows that, α R g less than α R。 This means that the temperature coefficient of the bridge arm resistance of a series of compensation resistors is less than the bridge arm resistance itself.

Ar g = (RT g) − (r zero g) r zero g × One t − t zero = RT − r zero r zero g × One t − t zero

（6）

Figure 3 shows the position t of the temperature coefficients g and R of the total resistance of the parallel resistance α R ‖ g, as in equation (7). Comparison with equation (5) shows that, α R ‖ g less than α R. This means that a compensation resistance is less than the temperature coefficient of the bridge arm resistance of the bridge arm parallel resistance itself.

AR ‖ g = RT ‖ g − r zero ‖ GR zero ‖ G × One t − t zero = GR zero g (RT − r zero r zero) × One t − t zero) = one RTG one × aB

(VII)

The symbol "‖" indicates that two resistors are connected in a parallel relationship.

From the above analysis, we can infer that increasing or reducing the series compensation resistance and parallel compensation resistance can reduce the temperature coefficient and adjustment offset of the bridge arm resistance with the compensation resistance. This is the compensation principle for offset voltage and bias temperature coefficient.

2.2。 Sensitivity temperature coefficient compensation

Figure 4 compensation of bridge sensitivity

V out = V in (Rb (T) Rb (T) RS) × S（T） × P

（8）

III Passive resistance temperature compensation model and algorithm

Figure 5 passive resistance temperature compensation model and a constant voltage: (I) initial negative bias voltage; (b) positive initial offset voltage

Figure 5 of the compensation model can be analyzed as follows:

Factors affecting partial pressure:

K (T, P) = RZ r four (T, P) RZ r four (T, P) r one (T, P) ‖ RP

（12）

K_ (T,P)=R3(T,P)R2(T,P)+R3(T,P)

（13）

According to the temperature compensation requirements of the bridge, the passive resistance temperature compensation algorithm can be written as:

⎧⎩⎨⎪⎪⎪⎪⎪⎪TOUT(T0,P0)=U0 Compensation of offset voltage U0∂VOUT(V,P0)∂T=0 Compensation of temperature coefficient of offset∂VOUT(V,P1)∂T=0 Compensation of temperature coefficient of sensitivity

（15）

R values Z, RP, RS in the passive resistance temperature compensation model can be determined by equation (15) using computer software such as MATLAB

4。 Experiment and data processing

Fig. 6 developed high temperature pressure sensor and its manufacturing process: (I) high temperature pressure sensor; (b) manufacturing process of micro electro mechanical system (MEMS).

Fig. 7 development of high temperature and pressure calibration device.

Figure 8 shows the test results of compensated high temperature pressure sensor: (1) output voltage calibration curve under temperature and pressure environment; (b) thermal zero drift; (c) thermal sensitivity drift

Fig. 9 shows the test results of compensated high temperature pressure sensor and traditional temperature compensation model and empirical algorithm: (1) output voltage calibration curve under temperature and pressure environment; (b) thermal zero drift; (c) thermal sensitivity drift

Table 2 test results of bridge arm resistance under different environmental conditions.

Fig. 10 solves the equation by plotting the parameter space.

The parameter values are different in the following compensation resistance ranges:

RZ∈[0, 200 Ω],RP∈[1 kΩ,1000 kΩ],RS∈[1 KΩ,30 kΩ]

The passive resistance temperature compensation circuit is established through the data in Table 2. The resulting circuit is shown in FIG. 11

The sensor test results of passive resistance temperature compensation are shown in Figure 12. In the operating temperature range, the total accuracy is ± 1.5% FS, the maximum thermal zero drift is 1.8% FS, and the maximum thermal sensitivity drift is − 4.6%.

From the above results, it is clear that the calibration curve of the uncompensated sensor (Fig. 8) shows obvious changes in the temperature range. The calibration curve of the sensor is compensated by the traditional method within the temperature range with improved overall accuracy (Fig. 9). However, the passive resistance temperature compensation proposed by the sensor calibration curve (Fig. 12) clearly shows the best accuracy over the whole temperature range. Obviously, passive resistance temperature compensation is more effective than traditional temperature compensation because it leads to higher measurement accuracy in the experimental temperature range.

Principle of high temperature pressure sensor

Fig. 13 is a schematic diagram of a high temperature signal conditioning circuit.

The test results of temperature compensation and passive resistance high temperature signal conditioning circuit for high temperature piezoresistive pressure sensor are shown in Figure 14 and compared with the performance of corresponding xte-190 sensor (listed by kulite) in Table 3

Table 3 performance comparison of similar sensor parameters.

In addition, in order to fully verify the effect of passive resistance temperature compensation, the same batch of six sensors has completed the temperature compensation calibration test with the same method, and the compensation effect has reached the same level. The sensor device shown in the picture is shown in Figure 15

Pressure sensor temperature compensation

In this paper, we propose a widely applicable method for passive resistance temperature compensation of high temperature piezoresistive pressure sensor. This method uses an algorithm based on differential equation. Our passive resistance temperature compensation technology is not affected by the characteristic deviation between the bridge arm resistance or residual stress. At different temperatures and different load pressure thresholds, only the measurement of four leg resistance, temperature compensation circuit and compensation parameters can be used to determine the calculation. In addition, the high temperature signal conditioning circuit can be used to improve the output sensitivity of the compensation sensor. The compensation effect of passive resistance temperature compensation in high temperature pressure sensor has been proved to be significantly better than the traditional compensation technology in a wide temperature and pressure range, which shows that our method is worthy of popularization in sensor fabrication.