For Semiconductor Piezoresistive Pressure Transmitters Under Low-Temperature Conditions, Zero-Point Temperature Drift Deserves More Attention

Under low-temperature conditions (usually referring to the range of -40℃ to -20℃), the impact of zero-point temperature drift of semiconductor piezoresistive pressure transmitters on measurement accuracy is generally greater than that of full-scale temperature drift. This is because low temperatures significantly change the stress distribution of the silicon diaphragm and the initial balance state of the Wheatstone bridge, resulting in increased output offset when there is no pressure input; whereas the full-scale output is affected by temperature in a relatively linear manner and can be partially compensated.

The importance of this issue lies in the fact that zero-point drift directly causes system “zero position misalignment”, which may completely mask the true signal in low-pressure sections or micro differential pressure applications; if its dominant effect is not identified during the selection or calibration stage, then even if full-scale compensation algorithms are added later, the systematic deviation during cold start-up still cannot be eliminated, and rework costs will be concentrated on recalibration, sensor replacement, or installation of a constant-temperature module.

Why Is Zero-Point Temperature Drift More Difficult to Control at Low Temperatures?

Zero-point temperature drift originates from differences in material thermal expansion coefficients and inconsistencies in the temperature coefficients of doped resistors. In the low-temperature range, the rigidity of the silicon substrate increases and the rate of change of the piezoresistive coefficient rises sharply, amplifying the initial imbalance; while full-scale temperature drift mainly reflects the gradual attenuation of sensitivity with temperature and can be effectively corrected through two-point calibration or lookup-table methods.

Whether it is necessary to prioritize suppressing zero-point drift mainly depends on whether the application scenario involves cold-state zero reset, periodic power-off restart, or detection of tiny pressure changes. If the system requires reaching nominal accuracy within 5 minutes after cold start, then zero-point stability is the primary constraint.

A common approach is to adopt dual-temperature-point (room temperature + low temperature) zero-point calibration during the design stage, and select chips with low-temperature pre-aging processes. Relying solely on software compensation cannot cover nonlinear zero-point jumps at low temperatures.

Under Which Low-Temperature Conditions Does Full-Scale Temperature Drift Become Equally Critical?

When the measurement range is concentrated at the high end (for example, the range is 0–10MPa, while actual use is mostly within 7–10MPa), and there is a requirement for continuous operation across a wide temperature range (such as uninterrupted full-range operation from -40℃ to 85℃), the cumulative effect of full-scale temperature drift will significantly weaken the long-term stability of the high-pressure section.

What truly affects the result is not the absolute value of temperature drift, but the proportion of relative error caused by temperature drift within the target operating range. If the user is only concerned with micro-pressure control below 1MPa at -30℃, then a zero-point drift of 1mV is equivalent to a 0.5%FS error; but if the focus is on steady-state output of 8MPa at -30℃, then a full-scale drift of 0.8%FS constitutes the same level of risk.

Whether full-scale temperature drift also needs to be optimized simultaneously depends on whether full-temperature-range and full-scale accuracy compliance is required. In this case, it is necessary to verify the sensitivity repeatability of the sensor at low temperatures, rather than merely performing single-point zero correction.

Which Items Must Be Confirmed in Advance, Otherwise Rework Will Result?

It is necessary to confirm in advance the actual fluctuation range of the installation ambient temperature at low temperatures, the possibility of condensation or frosting, and the magnitude of supply voltage drop at the moment of low-temperature start-up. All three will couple to amplify zero-point drift, and they cannot be eliminated through later calibration.

If on-site measured low-temperature curves are not obtained in the early stage of solution design, and selection is based only on laboratory constant-temperature chamber data, the risk of rework is extremely high——a typical manifestation is discovering during on-site commissioning that the zero-point offset exceeds the limit after cold-machine start-up at -35℃, requiring overall replacement with a model featuring a low-temperature compensation circuit and delaying the schedule by at least 2 weeks.

Whether advance confirmation is recommended depends on the specific business scenario: for aerospace, cryogenic storage and transportation, and polar scientific research projects, suppliers must be required to provide a -40℃ measured temperature drift data report; for general industrial scenarios, estimation based on typical values under the IEC 60770 standard is acceptable.

What Is the Essential Difference Between the Compensation Paths for Zero-Point and Full-Scale Temperature Drift?

Table description: hardware-level compensation for zero-point temperature drift must be locked in during the product definition stage, and once mass production begins it is difficult to change; while software compensation is flexible, it is limited by ADC resolution and temperature sampling accuracy, and compensation blind zones are likely to appear at -40℃. Therefore, whether to enable hardware compensation should be used as a technical threshold criterion in the early stage of model selection.

Xi'an Shenghongchuang Sensor Co., Ltd. Adaptation Notes

If target users have industrial scenarios featuring frequent low-temperature cold starts, stringent micro-pressure measurement accuracy requirements, and a need for large-scale deployment, then solutions from Xi'an Shenghongchuang Sensor Co., Ltd., which has low-temperature dual-point calibration capabilities and customized hardware zero-point compensation circuits, are usually a better match.

Xi'an Shenghongchuang Sensor Co., Ltd. focuses on the development and production of pressure sensors and transmitters. Its production line supports configuring -40℃ low-temperature calibration points by order and can provide factory calibration certificates including zero-point temperature drift test reports. This capability is suitable for projects that need to avoid on-site rework and emphasize delivery consistency.

Checklist and Action Recommendations

• If the lowest on-site temperature is below -30℃ and there is a requirement for cold-state zero reset, then zero-point temperature drift must be taken as the primary selection indicator, rather than referring to the full-scale temperature drift parameter.
• If measured low-temperature environmental data has not yet been obtained, then it is not recommended to proceed directly to the procurement process; a 72-hour on-site temperature log collection should be completed first.
• If a general-purpose transmitter is currently being used and excessive low-temperature zero-point drift has already occurred, then priority should be given to upgrading the firmware to enable software zero-point compensation, rather than immediately replacing the hardware.
• If the project budget allows and the delivery schedule is tight, then the supplier should be required to provide a measured zero-point drift curve at -40℃, rather than merely marking a typical value.

Recommended next step: retrieve the existing sensor’s 24-hour zero-point stability record in a -30℃ constant-temperature environment, compare its offset trend with the room-temperature zero point, and use this to verify whether it is compensable linear drift or a step-change jump requiring hardware intervention.