Signal conditioning of pressure sensors

Basic pressure sensors

Piezoresistive pressure sensors consist of a thin silicon diaphragm on which electrical resistors are implanted and connected to form a bridge circuit. When under pressure the powered bridge outputs a mV signal (typ. 100 mV Full Scale) with design and production related tolerances in respect to zero pressure offset and pressure sensitivity. Additionally, the pressure sensitivity as well as the bridge resistance are temperature dependent and change across the operating temperature range of the sensor.

Basic pressure sensors offer cost benefits, however the customer has to calibrate and compensate these sensors across the operating temperature range using complex electronics.

Calibrated and temperature compensated pressure sensors

Pressure sensors in this category are factory calibrated and temperature compensated with tight tolerances from one sensor to the next. The zero pressure offset and full scale span are calibrated to a uniform value for all sensors. Further, the temperature effects on the sensor output signal are compensated across the operating temperature range. Sensortechnics' calibrated and temperature compensated pressure sensors use passive resistor networks which are precision laser-trimmed for each individual device.

Calibrated and temperature compensated pressure sensors can be easily and flexibly integrated into the customer's electrical circuit and allow for the sensors to be quickly replaced without having to recalibrate the system.

Amplified pressure sensors

Amplified pressure sensors supply industrial standard signals (0.5...4.5V, 4...20 mA, etc.) or digital interfaces (I²C, SPI). Conventional calibration, temperaturecompensation and amplification are achieved using analog circuits withoperational amplifiers. Sensortechnics' new generation of digital pressuresensors directly corrects the sensor signal electronically using amicroprocessor. The benefit of this method is that all parameters such asoffset, span, temperature effects and non-linearity are corrected as a completesystem.

Sensortechnics' amplified pressure sensors achieve very high accuraciesacross wide temperature ranges and offer excellent price/performance ratios.The pressure measurement values can be directly processed without furtherexternal signal conditioning. Using the digital interface, the pressure sensorcan directly communicate with the systems microprocessor without the need for additionalelectronics.