The Micro Pirani Gauge with Low Noise CDS-CTIA for In-Situ Vacuum Monitoring

Kim, Gyungtae; Kim, Tae Hyun; Park, Jae Hong; Kim, Heeyeoun; Ko, Hyoungho

doi:10.5573/jsts.2014.14.6.733

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…Figure 1 shows a block diagram of the proposed capacitive sensing circuit. The capacitive sensing chain adopts the correlated double sampling (CDS) technique to reduce the low frequency noise, including the 1/f noise [ 8 , 9 , 10 ]. The capacitive sensing chain is composed of three amplification stages.…”

Section: Circuit Descriptionmentioning

confidence: 99%

Fully Integrated Low-Noise Readout Circuit with Automatic Offset Cancellation Loop for Capacitive Microsensors

Song

Park

Kim

et al. 2015

Sensors

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Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL) for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR) logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS) process with an active area of 1.76 mm2. The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of −250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms.

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Section: Circuit Descriptionmentioning

confidence: 99%

Fully Integrated Low-Noise Readout Circuit with Automatic Offset Cancellation Loop for Capacitive Microsensors

Song

Park

Kim

et al. 2015

Sensors

Self Cite

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“…In addition, the Pirani gauges in references [ 1 , 2 , 3 , 7 , 8 ] have generally smaller ranges. Furthermore, the Pirani gauges in references [ 4 , 9 , 10 , 11 , 12 , 13 , 14 ] have problems relating to complex structure, difficult manufacturing processes, and high cost. The Pirani gauges in references [ 4 , 15 , 16 ] have a similar dynamic range as those in our work, but reference [ 4 ] uses ion implantation to form a diode as the thermal layer, which greatly increases the complexity of the process.…”

Section: Introductionmentioning

confidence: 99%

Design of a High Sensitivity Pirani Gauge Based on Vanadium Oxide Film for High Vacuum Measurement

Guo

Feng

Chen

et al. 2022

Sensors

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We have designed a hot-plate-type micro-Pirani vacuum gauge with a simple structure and compatibility with conventional semiconductor fabrication processes. In the Pirani gauge, we used a vanadium oxide (VOx) membrane as the thermosensitive component, taking advantage of the high temperature coefficient of resistance (TCR) of VOx. The TCR value of VOx is −2%K−1∼−3%K−1, an order of magnitude higher than those of other thermal-sensitive materials, such as platinum and titanium (0.3%K−1∼0.4%K−1). On one hand, we used the high TCR of VOx to increase the Pirani sensitivity. On the other hand, we optimized the floating structure to decrease the thermal conductivity so that the detecting range of the Pirani gauge was extended on the low-pressure end. We carried out simulation experiments on the thermal zone of the Pirani gauge, the width of the cantilever beam, the material and thickness of the supporting layer, the thickness of the thermal layer (VOx), the depth of the cavity, and the shape and size. Finally, we decided on the basic size of the Pirani gauge. The prepared Pirani gauge has a thermal sensitive area of 130 × 130 μm2, with a cantilever width of 13 μm, cavity depth of 5 μm, supporting layer thickness of 300 nm, and VOx layer thickness of 110 nm. It has a dynamic range of 10−1~104 Pa and a sensitivity of 1.23 V/lgPa. The VOx Pirani was designed using a structure and fabrication process compatible with a VOx-based uncooled infrared microbolometer so that it can be integrated by wafer level. This work contains only our MEMS Pirani gauge device design, preparation process design, and readout circuit design, while the characterization and relevant experimental results will be reported in the future.

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