Calibration of pressure sensors in high temperature applications

Abstract

An improved pressure sensor includes a passive signal conditioning circuit for use in high-temperature environments. The passive signal conditioning circuit includes a number of blocks. Each of the blocks includes a thermistor, a first resistor in series with the thermistor, and a second resistor in parallel with the thermistor. In examples, a first block may correspond to a first temperature range, a second block may correspond to a second temperature range, and a third block may correspond to a third temperature range.

Description

Calibration of Pressure Sensors in High Temperature ApplicationsCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of US Provisional Patent Application No. 63 / 558,390, filed February 27, 2024, and titled “Calibration of Pressure Sensors in High Temperature Applications,” the entirety of which is hereby incorporated by reference.FIELD OF THE TECHNOLOGY

[0002] The subject disclosure relates to sensing devices, such as pressure sensors. More specifically, this disclosure relates to calibration of pressure sensors configured for use in high temperature applications.BACKGROUND OF TECHNOLOGY

[0003] Conventional pressure sensors are used in many applications. These conventional sensors may include signaling conditioning circuits. However, these conventional devices and associated circuits may not be rated for use in certain operating environments. For example, some conventional sensors may not be rated for use in high temperature applications, including those associated with some aerospace applications, such as jet engines. For example, such applications may require sensors that can withstand temperatures up to or exceeding 250-degrees Celsius.

[0004] Some conventional designs use application specific integrated circuit (ASIC) circuitry with pressure sensors. However, if the conventional circuitry with ASIC is used, the ASIC may be damaged permanently at high operating temperatures. This will result in sensor failure. In contrast, if a conventional schematic for standard unamplified pressure sensors is used, because it is designed for thermal compensation up to 150°C only, at higher temperatures, theelectrical circuit may not compensate for the thermal drift of the MEMS die. In some examples, the compensation circuit may actually become a source of error when exceeding 150°C and may drastically degrade the pressure sensor accuracy.

[0005] Accordingly, there is a need in the art for improved sensing devices, such as pressure sensors, capable of use in different operating conditions, and particularly in high temperature operation conditions.SUMMARY OF THE TECHNOLOGY

[0006] The subject technology relates to improved pressure sensors. In examples, aspects of this disclosure relate to pressure sensors for use in high temperature applications. For example, aspects of this disclosure relate to improved circuits for signal conditioning (e.g., calibration) of micro-electro-mechanical system (MEMS) type pressure sensors. Sensors according to this disclosure may be configured for use in operating temperatures of from about -55-degrees Celsius to about 250-degrees Celsius.

[0007] Aspects of this disclosure relate to an electrical schematic to calibrate high temperature pressure sensors. The circuit may use a combination of PTC and NTC thermistors (for example, 6 thermistors total) to compensate for the thermal drift of the Piezoresi stive MEMS die at Cold, Hot, and Extreme Hot temperatures. The developed sensors may have accuracy of ±1% Full Scale within the entire operating temperature range (-55°C to 250°C). As reference, sensors without any thermal compensation (no thermistors) have ±4% F.S. accuracy, which may be insufficient for some implementations.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that those having ordinary skill in the art to which the disclosed systems and techniques pertain will more readily understand how to make and use the same, reference may be had to the following drawings.

[0009] FIG. l is a schematic representation of a passive signal conditioning circuit for use with a high-temperature MEMS pressure sensor, in accordance with aspects of this disclosure.

[0010] FIG. 2 is a table providing details of aspects of the passive signal conditioning circuit of FIG. 1, in accordance with aspects of this disclosure.

[0011] FIGS. 3A and 3B are perspective and cross-sectional perspective views, respectively, of high temperature pressure sensors, in accordance with aspects of this disclosure.

[0012] FIGS. 4A and 4B are perspective views of, respectively, non-oil-filled and oil-filled header assemblies for use in high temperature pressure sensors, in accordance with aspects of this disclosure.

[0013] FIG. 5 shows top and bottom plan views of an example of a signal conditioning printed circuit board for use in high temperature pressure sensors, in accordance with aspects of this disclosure.

[0014] FIG. 6 is a graph illustrating a comparison of operating temperatures of different types of MEMS pressure sensors with different types of signal conditioning circuits, in accordance with aspects of this disclosure.

[0015] FIG. 7 illustrates an example of the passive signal conditioning circuit of FIG. 1, with defined resistor values, in accordance with aspects of this disclosure.

[0016] FIG. 8 is a schematic representation of an alternative configuration of a passive signal conditioning circuit with a high-temperature MEMS pressure sensor, in accordance with additional aspects of this disclosure.

[0017] FIG. 9 is a schematic representation of an additional alternative configuration of a passive signal conditioning circuit with a high-temperature MEMS pressure sensor, in accordance with additional aspects of this disclosure.

[0018] FIG. 10 is a schematic representation of yet an additional alternative configuration of a passive signal conditioning circuit with a high-temperature MEMS pressure sensor, in accordance with additional aspects of this disclosure.

[0019] FIG. 11 includes graphs showing test results associated with oil-filled MEMS pressure sensors implementing the techniques detailed herein, in accordance with aspects of this disclosure.

[0020] FIG. 12 includes graphs showing test results associated with not oil-filled MEMS pressure sensors implementing the techniques detailed herein, in accordance with aspects of this disclosure.DETAILED DESCRIPTION

[0021] The subject technology overcomes many of the prior art problems associated with pressure sensors. In brief summary, the subject technology provides improved pressure sensors with improved signal conditioning circuits that facilitate use of such pressure sensors in a broad range of operating temperatures.

[0022] Without limitation, sensors designed in accordance with aspects of this disclosure provide very high sensor accuracy (±1.5%), and are able to withstand temperature points as high as 250°C when exposed in the field. In some examples, sensors made in accordance with this disclosure may provide four times better accuracy can be met across an entire operating temperature range of from about -55°C to about 250°C when employing the signal conditioning circuits disclosed herein. In examples shown herein, the output error reduces from ±4% F.S. when using no thermistor blocks to ±1% F.S. when implementing the described compensation circuit, as shown in FIGS. . Such performance may meet specifications that can require 200°C, 230°C, or 250°C max operating temperature with accuracies ranging from ±1.5% F.S. up to ±3% F.S.

[0023] Aspects of the disclosure will now be explained in more detail with reference to the Figures.

[0024] FIG. 1 is a schematic 100 representation of a passive signal conditioning circuit 102 for use with a pressure sensor 104, which may be a high-temperature MEMS pressure sensor.

[0025] Specifically, the disclosed schematic 100 includes six blocks of resistors and thermistors, specifically, for which the resistance value changes with temperature. Two types of thermistors are used in this schematic to compensate for thermal drift of the MEMS die, namely, PTC (Positive Temperature Coefficient) thermistors for which the resistance value of the thermistor increases with temperature and NTC (Negative Temperature Coefficient) thermistors for which the resistance value of the thermistor decreases with temperature. More specifically, the schematic uses 1000 PTC, 500 NTC, and 30 k NTC for thermal compensation at Cold, Hot, and extreme Hot temperatures, respectively. The thermistors are connected to the resistors in seriesand parallel for which the values are tailored to better match with the required amount of compensation for each individual MEMS die.

[0026] In more detail, the passive signal conditioning circuit 102 includes a pressure sensor 104, which is illustrated as a MEMS die. As detailed further herein, the pressure sensor 104 may be an oil-filled MEMS pressure sensor or a not oil-filled MEMS pressure sensor.

[0027] The passive signal conditioning circuit 102 also includes two resistors, R1 and R2, arranged in parallel and coupled to the pressure sensor 104. The two resistors R1 and R2 may be provided as an offset adjustment of an output of the pressure sensor 104 The passive signal conditioning circuit 102 also includes two resistors, R3 and R4, coupled to the pressure sensor. These resistors, R3 and R4 may be provided as an offset for thermal compensation. Thus, the resistors R1-R4 may be used to “zero” the sensor, e.g., to compensate for output imbalances and / or effects of temperature changes.

[0028] As noted above, the passive signal conditioning circuit 102 includes six blocks, each comprising one or more resistors and / or one or more thermistors. A first block 106 and a second block 108 are substantially the same, a third block 110 and a fourth block 112 are substantially the same, and a fifth block 114 and a sixth block 116 are substantially the same. The blocks 106, 108, 110, 112, 114, 116 are provided for span thermal compensation, as described further herein.

[0029] As illustrated in FIG. 1, the first block 106 includes two resistors R5, R6 and a first thermistor 118. The resistor R6 and the first thermistor 118 are connected in series. The resistor R5 is connected in parallel with the resistor R6 and the first thermistor 118. As noted, the second block 108 is substantially the same as the first block 106. Specifically, in FIG. 1, the second blockincludes two resistors R7, R8 and a second thermistor 120. The resistor R8 and the second thermistor 120 are connected in series. The resistor R7 is connected in parallel with the resistor R8 and the second thermistor 120. In examples, the first and second thermistors 118, 120 are negative temperature coefficient (NTC) thermistors. In one non-limiting example, the first and second thermistors 118, 120 may have a beta sensitivity coefficient of 3892. In the illustrated example, the first and second thermistors 118, 120 may be configured to provide span thermal compensation at extremely high temperatures, e.g., over about 150-degrees Celsius.

[0030] The third block 110 includes two resistors R9, R10 and a third thermistor 122. The resistor R10 and the third thermistor 122 are connected in series. The resistor R9 is connected in parallel with the resistor R10 and the third thermistor 122. As noted, the fourth block 112 is substantially the same as the third block 110. Specifically, in FIG. 1, the fourth block includes two resistors R11, R12 and a fourth thermistor 124. The resistor R12 and the fourth thermistor 124 are connected in series. The resistor R11 is connected in parallel with the resistor R12 and the fourth thermistor 124. In examples, the third and fourth thermistors 122, 124 are negative temperature coefficient (NTC) thermistors. In one non-limiting example, the third and fourth thermistors 122, 124 may have a beta sensitivity coefficient of 2941. In the illustrated example, the third and fourth blocks 110, 112 may be configured to provide span thermal compensation at high temperatures, e.g., from about 25-degrees Celsius to about 150-degrees Celsius.

[0031] The fifth block 114 includes two resistors R13, R14 and a fifth thermistor 126. The resistor R14 and the fifth thermistor 126 are connected in series. The resistor R13 is connected in parallel with the resistor R14 and the fifth thermistor 126. As noted, the sixth block 116 is substantially the same as the fifth block 114. Specifically, in FIG. 1, the sixth block includes two resistors R15, R16 and a sixth thermistor 128. The resistor R16 and the sixth thermistor 128 areconnected in series. The resistor R15 is connected in parallel with the resistor R14 and the sixth thermistor 128, In examples, the fifth and sixth thermistors 126, 128 are positive temperature coefficient (PTC) thermistors. In the illustrated example, the fifth and sixth blocks 114, 116 may be configured to provide span thermal compensation at low, e.g., cold temperatures, for instance from about -55-degrees Celsius to about 25-degrees Celsius.

[0032] The passive signal conditioning circuit 102 also includes a resistor R17 in series with the first block 106, the third block 110, and the fifth block 114 and a resistor R18 in series with the second block 108, the fourth block 112, and the sixth block 116. The resistors R17, R18 are configured to provide span adjustment of an output of the sensor 104. The passive signal conditioning circuit 102 also includes a resistor R19 disposed across outputs of the sensor 104 and a resistor R20 disposed across inputs, e.g., input terminals of the passive signal conditioning circuit 102. The resistor R19 may be provided as an output impedance adjustment and / or the resistor R20 may be provided as an input impedance adjustment.

[0033] As described above, the passive signal conditioning circuit 102 uses two types of thermistors: PTC & NTC (thermistors with Positive / Negative Temperature Coefficient). More precisely, one example uses a 1000 PTC, a 500 NTC with Beta sensitivity coefficient of 2941, and a 30 k NTC with Beta sensitivity coefficient of 3892. As discussed above, each thermistor is connected to a first resistor in series and a second resistor in parallel, with the thermistor, first resistor and second resistor forming one block. In the example of FIG. 1 discussed above, there are three thermal compensation blocks at the bottom of the schematic, e.g., associated with a first input terminal (blocks 106, 110, 114 of FIG. 1) and three substantially identical thermal compensation blocks on the top of the schematic, e.g., associated with a second input terminal (blocks 108, 112, 116 of FIG. 1).

[0034] As noted above, the disclosed schematic can be used for oil fdled MEMS (OFM) pressure sensors as well as Not Oil-filled MEMS pressure sensors. As detailed further below, test results using the circuit 102 of the schematic 100 showed increased accuracy, e.g., about 4x times better accuracy (±1% F.S. versus 4% F.S.) across the entire operating temperature range (-55 to 250°C) when using the circuit 102 with described thermistor blocks.

[0035] FIG. 2 includes a table 200 summarizing the function(s) of each of the components in the schematic 100, as discussed above.

[0036] FIG. 3 A includes a perspective view of an example pressure sensor assembly 300 that may incorporate the passive signal conditioning circuit 102 (and sensor 104) discussed above. FIG. 3B is a perspective view of the sensor assembly 300, taken along the section line B — B in FIG. 3A.

[0037] As shown in FIGS. 3A and 3B, the pressure sensor assembly 300 generally includes a pressure port 302 at a first end of a housing 304 and a connector 306 coupled to the housing 304. The pressure port 302 is illustrated as including threads 308, which are an example of an attachment feature for securing the pressure sensor assembly 300 to a pressurized volume (not shown). Once attached, pressurized fluid in the volume passes through a channel 310 extending through the pressure port 302 to interface with a header assembly 312.

[0038] The header assembly 312 may include the pressure sensor 104, which may be a MEMS die assembly. In examples of this disclosure, the MEMS die assembly is configured to generate electrical signals in response to pressure applied at the MEMS die by a fluid in the channel 310. As also illustrated, the header assembly 312 can include one or more pins 314. The pin(s) 314 electrically connect aspects of the header assembly 312. For example, and in the illustratedexample, the pin(s) 314 electrically connect the pressure sensor 104 to a signal conditioning printed circuit board (PCB) 316, The signal conditioning PCB 316 includes the passive signal conditioning circuit 102, discussed above.

[0039] The connector 306 is configured to facilitate connection of an external system (not shown) to the pressure sensor assembly 300. In the illustrated example, the connector 306 comprises external threads 318, e.g., to facilitate threaded connection of a mating conduit, cable, or the like. In other examples, the connector 306 may include additional and / or different features for facilitating connection. The connector 306 also is illustrated as including connection pins 320, which may be configured to transfer and / or receive power, data, and / or the like. External ends of the connection pins 320 extend away from the housing 304 and are disposed for contact by the connected device. Internal ends of the connection pins 320 may be coupled to a connector circuit board 322, which may be a printed circuit board, for example. Although not illustrated in FIG. 3B, the connector circuit board 322 may be electrically coupled to the pressure sensor 104 and / or to the signal conditioning PCB 316. Without limitation, the connector circuit board 322 can receive pressure data from the pressure sensor 104 and transmit such pressure data to an external system, a user interface, and / or the like.

[0040] FIGS. 4A and 4B are perspective views of instances of the header assembly 312 discussed above. Specifically, FIG. 4A shows a first header assembly 400 that is an example of a not oil-filled header assembly. As shown in FIG. 4A, the first header assembly 400 includes the pressure sensor 104 and wire bonds 402 connecting the pressure sensor 104 to the pins 314. In the illustrated example, five instances of the pins 314 are illustrated. Each of the pins 314 may be connected to one of the OUT-, OUT+, IN+, -INN, and the -INP connections shown in the schematic of FIG. 1, discussed above, for example.

[0041] FIG. 4B shows a second header assembly 404 that is an example of an oil-filled header assembly. As shown in FIG. 4B, the second header assembly 404 includes a diaphragm 406 disposed over the pressure sensor 104. For example, the diaphragm 406 may be a corrugated diaphragm. Although not visible in FIG. 4B, the diaphragm 406 defines, with other portions of the header assembly 404, a volume containing the sensor 104. The volume is filled with an oil, such as silicone oil.

[0042] As will be appreciated, the first header assembly 400 may be disposed in a pressure sensor assembly 300 such that the pressure sensor 104 is directly exposed to pressurized contents to be measured, e.g., via the pressure port 302. The second header assembly 404, instead, is disposed in the pressure assembly 300 such that the diaphragm 406 is exposed to the pressurized contents.

[0043] FIG. 5 shows top and bottom views of an example of the signal conditioning PCB 316, according to examples of this disclosure. As illustrated, a board or substrate 502 is shaped for placement in the housing 304. As also illustrated, a number of resistors 504 and thermistors 506 are disposed on the substrate 502 and interconnected via traces 508.

[0044] FIG. 6 includes a graphic 600 showing the application ranges for MEMS pressure sensors with different types of signal conditioning circuits. For example, FIG. 6 shows that an unamplified circuit with six thermistors (formed as a passive circuit), like the circuit 100, is useful in additional (high) temperature ranges, compared to an amplified application specific integrated circuit (ASIC) and an unamplified circuit with four thermistors (as a passive circuit). For example, and as detailed herein, pressure sensors incorporating the passive signal conditioning circuitaccording to aspects of this disclosure may be used across larger and / or higher temperature ranges than conventional pressure sensors.

[0045] As will be understood from FIG. 6, there may be two ways to calibrate MEMS pressure sensors.

[0046] A first is via an active circuit, as represented by a first bar 602 in the graphic 600. In the active circuit method, an ASIC may be used to signal condition the output of the Piezoresistive MEMS die. This is used in many conventional sensors. However, due to the ASIC performance limits (high current leakage at high temperatures), the maximum operating temperature of the sensor may be limited to a maximum temperature of around 120°C or 130°C. To achieve higher temperatures, the second method should be used.

[0047] The second method is via a passive circuit, as represented by a second bar 604 and a third bar 606 in the graphic 600. The passive circuit uses a combination of resistors and thermistors (no active components) to adjust the offset and span, and compensate for the thermal drift of the Piezoresistive MEMS die. Some calibration schemes, illustrated by the second bar 604, may use four thermistors to achieve higher sensor accuracy, e.g., up to about 150°C. In contrast, the passive circuit according to this disclosure, e.g., the passive signal conditioning circuit 102, allows for use of a piezoresistive MEMS die in high-temperature applications (e.g., in temperatures from about -55°C up to about 250°C).

[0048] In examples of this disclosure, unlike some conventional sensors, a silicon on insulator (SOI) die may be used. Some conventional sensors use a simple silicon die, for instance. Due to lack of the electrical insulation layer in conventional silicon dies, however, at high temperatures the current leakage increases across opposite doped zones of silicon, introducinghigher errors to the output signal. SOI dies according to this disclosure may benefit from the insulation layer which minimizes the amount of the current leakage between the piezoresistive resistors and the substrate, making them more suitable for high-temp applications. Because of such differences, SOI dies and silicon dies do not have the same thermal performances, so the arrangement of conventional circuits cannot be used. That is, transferring a conventional circuit to a SOI die will not provide the desired usability at increased temperatures. Instead, at temperature points higher than 150°C, the thermistors themselves become a source of error because their resistance value drifts from the required compensation value. Consequently, the sensor accuracy deteriorates at extreme high temperatures.

[0049] FIG. 7 shows the schematic 100 with defined resistor values. For example, the resistor values can be determined empirically, theoretically, and / or via some other methodology. The resistor values of FIG. 7 are for example only.

[0050] Modifications to the passive signal conditioning circuit 102 also are contemplated. For example, any depiction of a resistor may be representative of multiple resistors in series. Moreover, a 1000 PTC thermistor may be replaced by a number of lower ohm PTC thermistors that add to 1000 ohms, e.g., two PTC thermistors of 500 Q.

[0051] FIG. 8 shows an alternative schematic 800 in which the order of the blocks has changed, as illustrated. For example, the first block 106 and the third block 110 are switched in the schematic 800 relative to the schematic 100. Also in FIG. 8, the second block 108 and the sixth block 116 are switched, relative to the schematic 100. Other modifications to the ordering of the blocks may also be made while still providing reliable performance including at high temperatures. For example, the order of the blocks 106, 108, 110, 112, 114, 116 and of the resistorsR17, R18 may be modified. For example, the resistor R17 may be placed anywhere in series with the first block 106, the third block 110, and the fifth block 114, and / or the resistor R18 may be placed anywhere in series with the second block 108, the fourth block 112, and the sixth block 116.

[0052] Still further modifications also are contemplated. For instance, if the common mode voltage (e.g., the voltage across +OUT and -IN terminals and voltage across -OUT and -IN terminals) is not a requirement for the sensor, the bottom blocks (e.g., the first block 106, the third block 110, and the fifth block 114) and the top blocks (e g., the second block 108, the fourth block 112, and the sixth block 116) can be arranged in any order. For instance, all six of the blocks may be placed in series between one of the input terminals and the pressure sensor 104, e.g., all at a top of the circuit or all at a bottom of the circuit. Also in these examples, the two resistors R17 and R18 may be combined into a single resistor.

[0053] FIG. 9 shows another alternative schematic 900. In this example, only three blocks are included. Specifically, the first block 106, the third block 110, and the fifth block 114 are illustrated. In other examples, only the second block 108, the fourth block 112, and the sixth block 116 may be included, for example. As will be appreciated, in these arrangements only one of each of the pairs of identical blocks is provided. While this arrangement may also be cheaper and / or easier to manufacture, e.g., because of the reduced components, this approach may comprise accuracy of the sensor output.

[0054] FIG. 10 shows yet another alternative schematic 1000 according to examples of this disclosure. Specifically, in FIG. 10, the third block 110 and the fourth block 112 are removed, when compared to the schematic 100. For example, depending on the required output accuracy ofthe sensor versus temperature, some of the thermal compensation blocks may not be required.While the arrangement of FIG. 10 may be cheaper and / or easier to manufacture, e.g., because of the reduced components, this approach may comprise accuracy of the sensor output. However, this increased possibility for error may be acceptable in some applications, while still providing pressure sensing at extremely high temperatures. In other examples, the fifth block 114 and the sixth block 116 may be removed, instead of the third block 110 and the fourth block 112, as shown in FIG. 10.

[0055] FIG. 11 includes graphs showing test results associated with oil-filled MEMS 100 PSIG pressure sensors. More specifically, FIG. 11 includes a first graph 1102 showing accuracy of a system that is calibrated with no thermistors (e.g., resistors only) and a second graph 1104 showing accuracy of a system that is calibrated using the passive signal conditioning circuit 102 described herein. As illustrated by the first graph 1102, the conventional techniques and systems may provide about 4% Full Scale accuracy over the temperature range of from about -50°C to about 250°C, with clear accuracy degradation at temperatures of about 200°C and higher. In contrast, and as illustrated by the second graph 1104, the techniques and systems described herein may provide less than about 1% Full Scale accuracy over the temperature range of from about -50°C to about 250°C. Thus, the systems and techniques disclosed herein improve accuracy in oil-filled MEMS pressure sensors.

[0056] FIG. 12 includes graphs showing test results associated with example not oil-filled MEMS 100 PSIG pressure sensors. More specifically, FIG. 12 includes a first graph 1202 showing accuracy of a system that is calibrated with no thermistors (e.g., resistors only) and a second graph 1204 showing accuracy of a system that is calibrated using the passive signal conditioning circuit 102 described herein. As illustrated by the first graph 1202, the conventional techniques and systems may provide about 3.5% Full Scale accuracy over the temperature range of from about -50°C to about250°C, with clear accuracy degradation at temperatures of about 200°C and higher. In contrast, and as illustrated by the second graph 1204, the techniques and systems described herein may provide less than about 1% Full Scale accuracy over the temperature range of from about -50°C to about 250°C. Thus, the systems and techniques disclosed herein improve accuracy in not oil-filled MEMS pressure sensors.

[0057] While the subject technology has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and / or modifications can be made to the subject technology without departing from the spirit or scope of the subject technology. For example, each claim may depend from any or all claims in a multiple dependent manner even though such has not been originally claimed.

Claims

WHAT IS CLAIMED IS:

1. A pressure sensor assembly comprising: a pressure sensor; and a signal conditioning printed circuit board (PCB), the signal conditioning PCB comprising a passive signal conditioning circuit electrically coupled to the pressure sensor and comprising a plurality of blocks, individual of the blocks including a thermistor, a first resistor arranged in series with the thermistor, and a second resistor arranged in parallel with the thermistor.

2. The pressure sensor assembly of claim 1, wherein the plurality of blocks comprise a first block, a second block, and a third block arranged in series.

3. The pressure sensor assembly of claim 2, wherein: the first block comprises a first negative temperature coefficient (NTC) thermistor having a first resistance; the second block comprises a second NTC thermistor having a second resistance different from the first resistance; and the third block comprises a first positive temperature coefficient (PTC) thermistor.

4. The pressure sensor assembly of claim 3, wherein: the first NTC thermistor has a first beta sensitivity coefficient; and the second NTC thermistor has a second beta sensitivity coefficient different from the first beta sensitivity coefficient.

5. The pressure sensor assembly of claim 4, wherein at least one of: the first NTC thermistor is a 30 k'Q NTC; or the second NTC thermistor is a 500 Q NTC.

6. The pressure sensor assembly of claim 4 or claim 5, wherein at least one of: the first NTC thermistor has a beta sensitivity coefficient of 3892; or the second NTC thermistor has a beta sensitivity coefficient of 2941.

7. The pressure sensor assembly of any one of claim 2 through claim 6, wherein: the first block is configured to provide span thermal compensation for a first temperature range; the second block is configured to provide span thermal compensation for a second temperature range; and the third block is configured to provide span thermal compensation for a third temperature range.

8. The pressure sensor assembly of claim 7, wherein the first temperature range is a relatively high temperature range, the third temperature range is a relatively low temperature range, and the second temperature range is a temperature range between the first temperature range and the third temperature range.

9. The pressure sensor assembly of any one of claim 2 through claim 8, wherein:the plurality of blocks further comprise a fourth block, a fifth block, and a sixth block arranged in series; the fourth block is substantially the same as the first block; the fifth block is substantially the same as the second block; and the sixth block is substantially the same as the third block.

10. The pressure sensor assembly of claim 9, wherein: the first block, the second block, and the third block are associated with a first input terminal of the passive signal conditioning circuit; and the fourth block, the fifth block, and the sixth block are associated with a second input terminal of the passive signal conditioning circuit.

11. The pressure sensor assembly of claim 10, wherein the passive signal conditioning circuit further comprises an input impedance resistor between the first input terminal and the second input terminal.

12. The pressure sensor assembly of claim 1, wherein: a first block of the plurality of blocks comprises a positive temperature coefficient (PTC) thermistor as the thermistor; and a second block of the plurality of blocks comprises a negative temperature coefficient(NTC) thermistor as the thermistor.

13. The pressure sensor assembly of claim 12, wherein the NTC thermistor is facilitates sensing by the pressure sensor at temperatures up to about 250-degrees Celsius.

14. The pressure sensor assembly of any one of claim 1 through claim 13, wherein the pressure sensor comprises a piezoresistive MEMS die including a silicon on insulator die.

15. The pressure sensor assembly of any one of claim 1 through claim 14, further comprising: a housing; a pressure port coupled to the housing and including a channel, the pressure port configured for coupling to a pressurized volume such that the channel is in fluid communication with the pressurized volume; and a header assembly disposed in the housing and including the pressure sensor, the header assembly being one of an oil-filled header assembly or a not oil-filled header assembly.

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