A Current-Controlled PCB Integrated MEMS Tilt Mirror

Abstract

Introduction: MEMS Tilt Mirror - a miniature planar micro-mirror that can experience a 1-D or 2-D tilt in response to a control signal. Commonly used technologies- electrostatic, piezoelectric, electrothermal bimorph. Applications - laser beam steering, interferometers, dynamic signal analyzers, opticcal cross-connect switches. This paper describes the design, key features and applications of a System On Chip (SOC) ASIC (Application Specific Integrated Circuit) that has been developed under an Air Force SBIR program. The SOC device has been implemented by Honeywell International using their High Temperature SOI (Silicon On Insulator) Process. The objective of the Air Force SBIR program {1} was to investigate the potential for use of available High Temperature SOI technology devices for aerospace propulsion control system applications. Several prototype designs implemented by Embedded Systems LLC (ES-LLC) using available SOI devices identified significant limitations in the performance capability and level of integration. The diversity of propulsion system interfacing requirements demanded generic solutions so that they could be deployed in multiple applications without changes. The available devices were also not affordable due to the limited size of the market for this technology. It was therefore decided to develop a generic, reconfigurable SOC chipset {2} that could be implemented using Honeywell's HT200 Family of ASIC Gate Arrays. The paper will describe the architecture and key features of the SOC chipset solution which can be reconfigured to interface with most typical aerospace control system sensors and actuators. The SOC chipset captures all of the necessary functions required to interface with sensors such as RTD (resistance Temperature Detectors), Strain Gauges (SG) and thermocouples (TC), mass flow, speed and LVDT (Linear Variable Differential Transducer) position. The excitation circuitry required to power these interfaces is embedded in the chipset and can be reconfigured as required. The SOC chipset also contains all of the pre- and post-processing functions to convert electrical signals into digital words and send them on a data bus under the control of a host microprocessor. The SOC chipset can be powered from a Mil-Std 704F compliant power source or a conditioned DC power source. The SOC chipset when combined with other external devices can be implemented as a “Smart Node” for localized management of sensors and actuators as a part of a distributed architecture or used as a scalable building block in a more complex function such as a FADEC (Full Authority Digital Engine Control). The SOC chipset thus completes the set of all High Temperature SOI Integrated circuits required for implementation of typical Smart Nodes. It is believed that the versatility of the SOC chipset makes it a well suited, affordable, scalable building block for not only aerospace controls but also for diverse applications such as down-hole drilling, energy exploration, wind farms etc. where high temperature electronics is required.