Speaker
Mr
Theodoros Athanasopoulos
(European Sensor Systems S. A)
Description
**European Sensor Systems** is a global developer and manufacturer of high quality sensors based on MEMS. In the course of the ESA activity 4000106328/12/NL/Cbi, European Sensor Systems is developing a “Space Qualified Family of MEMS Pressure Modules for Satellite Applications”.
![3D Model of Pressure Module][1]
**Figure 1: 3D Model of Pressure Module**
ESS has designed four MEMs sensors to cover the application’s pressure ranges (7, 22, 150, 310 bar) with dimensions 2×2×0.4 mm3 using X-FAB TM30P1111 technology, which is a combination of SOI, bulk and surface micro-machining process for the fabrication of capacitive pressure sensors. ESS is the IP owner and exclusive user of this process.
![Die photo of 22-bar MEMS][2]
**Figure 2: Die photo of 22-bar MEMS**
For interfacing with the MEMS, a custom radiation-hardened capacitive sensor signal conditioning ASIC has been designed. Based on the architecture of its commercial counterpart ASIC, ESS214 is built using X-FAB XH018 Process Design Kit, a 0.18 micron Modular Mixed Signal HV CMOS Technology. The output of the capacitance to voltage unit is converted to a 1-bit output by a second order ΣΔ modulator, which is down sampled and filtered in the digital part and finally converted to a 10-bit resolution PWM stream. The trimming of the device is performed via register programming using an I2C compatible Two-Wire Interface. A specific configuration can be written to the OTP memory once. The internal analog and digital regulator, the bandgap reference, the oscillator and the power-on reset eliminate the need of any additional components. Finally, a temperature sensor is embedded.
![ESS214 ASIC architecture and the MEMS interface][3]
**Figure 3: ESS214 ASIC architecture and the MEMS interface**
![Microphotograph of the Fabricated ESS214 ASIC][4]
**Figure 4: Microphotograph of the Fabricated ESS214 ASIC**
In order to address the problem of SEE the Triple Module Redundancy method with voting has been adopted. This mitigation scheme uses three identical logic circuits performing the same task in parallel with corresponding outputs being compared through a majority voter circuit. The technique has been applied at the level of digital synthesis. The TMR technique has been applied to all flip-flops of the digital part. For SEL immunity in the digital part, a library of custom digital cells has been designed and characterized in house to enhance radiation tolerance. The library contains combinational, sequential and special cells (layout fillers, antenna protection cells) and was based on cells that already exist in the digital library D_CELLSL_JI3V, which contains triple-well junction isolated cells. The increase of the layout area compared to a conventional cell varies from 2x to 4x. The library has been seamlessly integrated to the IC design flow. In the analog part, all PMOS devices have been enclosed by N-type guard rings and all the NMOS devices have been enclosed by P-type guard rings. Regarding TID ESS214 is designed using standard cells.
The CMOS ASIC has been tested for SEE (SEL/SEU) in the UCL cyclotron accelerator facility. The ASIC exhibited immunity to SEUs up to 32.4 MeV/(mg/cm^2) using Kr-769 and produced 2 SEUs at 62.50 MeV/(mg/cm^2) using Xe-995. The CMOS ASIC exhibited SEL immunity up to 62.5 MeV/(mg/cm^2) using Xe-995. The displacement damage test campaign is currently ongoing and results are expected soon.
[1]: http://www.esenssys.com/ess/images/pressure-scaled.png
[2]: http://www.esenssys.com/ess/images/mems-scaled.png
[3]: http://www.esenssys.com/ess/images/ess214_func_blockdiagram-scaled.jpg
[4]: http://www.esenssys.com/ess/images/asic-scaled.jpg
Primary author
Mr
Dimitrios Mitrovgenis
(European Sensor Systems S.A)
Co-author
Mr
Theodoros Athanasopoulos
(European Sensor Systems S. A)
