Bruce W. Ohme

Analog Component Development for 300°C Sensor Interface Applications

The development of Enhanced Geothermal Systems (EGS) for base-load electrical power generation will require electronics for sensing and control during exploration and drilling and also during production. The operating temperature environments for these applications will generally be more extreme than those encountered by electronics currently deployed for oil and gas development and production monitoring. To address this requirement, electronic components have been designed and fabricated for operation at temperatures of 300°C. These integrated circuits use silicon-on-insulator (SOI) fabrication processes to achieve high temperature operation. High-fidelity simulation models have been developed by characterization of SOI devices at 300°C. These device models were employed to design components required for the development of a down-hole orientation module. A wide-bandwidth, low-noise operational amplifier has been developed for use with MEMS accelerometer sensors. A multi-channel synchronous voltage-to-fre...

High Temperature Analog-to-Digital Converter Reliability Testing

Initial test results have been previously reported for a high-temperature (225°C) 12-bit analog-to-digital converter (HTADC12) fabricated using a production high-temperature silicon-on-insulator (SOI) CMOS process and assembled in hermetically sealed ceramic packages (ref. 1). Reliability test results for the HTADC12 are presented including parametric and functional test results from 1500 hours of dynamic life test at 250°C as well 1000 temperature cycles from −65°C to 200°C. Results of post-stress wirebond, and die bond testing are also provided.

Characterization of Circuit Blocks for Configurable Analog-Front-End

Analog functions have been implemented in a Silicon-on-Insulator (SOI) process optimized for high-temperature (>225°C) operation. These include a linear regulator/reference block that supports input voltages up to 50V and provides multiple independent voltage outputs. Additional blocks provide configurable sensor excitation levels of up to 10V DC and/or 20V AC-differential, with current limiting and monitoring. A dual-channel Programmable-GainInstrumentation Amplifier (PGIA) and a high-level AC input block with programmable gain and offset serve signal conditioning, gain, and scaling needs. A multiplexer and analog buffer provide an output that is scaled and centered for down-stream A-to-D conversion. Limited component availability and high component-counts deter development of sensing and control electronics for extreme temperature (>200°) applications. Systems require front-end power conditioning, sensor excitation and monitoring, response amplification, scaling, and multiplexing. Back-end Analog-to-Digital conversion and digital processing/control can be implemented using one or two integrated circuit chips, whereas the front-end functions require component counts in the dozens. The low level of integration in the available portfolio of SOI devices results in high component count when constructing signal conditioning interfaces for aerospace sensors. These include quasi-DC sensors such as thermocouples, strain-gauges, bridge transducers as well as AC-coupled sensors and position transducers, such as Linear Variable Differential Transducers (LVDT’s).Furthermore, a majority of sensor applications are best served by excitation/response voltage ranges that typically exceed the voltage range of digital electronics (either 5V or 3.3V in currently available digital IC’s for use above 200°C). These constraints led Embedded Systems LLC to design a generic device which was implemented by Honeywell as an analog ASIC (Application Specific Integrated Circuit). This paper will describe the ASIC block-level capabilities in the context of the typical applications and present characterization data from wafer-level testing at the target temperature range (225C). This material is based upon work performed by Honeywell International under a subcontract from Embedded Systems LLC funding for which was provided by the U.S. Air Force Small Business Innovative Research program.

A System On Chip (SOC) ASIC chipset for Aerospace and Energy Exploration Applications

This paper describes the design, key features and applications of a System On Chip (SOC) ASIC (Application Specific Integrated Circuit) chipset which was developed by Embedded Systems LLC as a part of the Smart Node based distributed control system architecture under an Air Force SBIR (Small Business Innovative Research) program {4}. The analog part of the SOC chipset has been implemented by Honeywell International under a subcontract using their high temperature SOI (Silicon On Insulator) Process. The complete chipset is expected to be available in early 2015. The key feature of the SOC chipset is that it is a reconfigurable and scalable building block that can be used to interface with most typical aerospace control system sensors and actuators. The SOC chipset captures all of the necessary functions required to power and interface with sensors such as RTD (Resistance Temperature Detectors), Strain Gauges (SG), Thermo Couples (TC) and transducers for measuring mass flow, speed, position or angle. The SO...