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High Performance Clock Oscillator

Description:

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics; Space Technology

 

OBJECTIVE: The Department of Defense(DoD) is seeking the development of a high performance, full in-system programmable, industrial  temperature rated (storage -55C to 125 C; operational -40 C to 105 C), US Sources, high G (30kG) operational shock, performance better than 0.001 ppb/g, 100kG survival shock, lower power (<30mW @ 1.8V), supply range 1.8 – 3.3V, microelectromechanical systems (MEMS) oscillator smaller than 9mm in area packaged and He proof, while capable of operations from 1 to 105 MHz with frequency stability of 0.5ppm in operational temperature range, the Allan deviation (ADEV ) better than 1E-11 in 1 to 9 Sec. The device shall be printed circuit board (PCB ) surface mountable with a large central electrically conductive pad for mechanical stability and seek to minimize the overall footprint and volume to the maximum extent possible.

 

DESCRIPTION: There are many applications for the DoD  which require high precision, low Size, Weight, Area and power (SWAP) clock sources. For example, satellite communications (SATCOM ), global navigation satellite system (GNSS)  receivers require reference clocks that have high frequency stability, low phase noise and low power operations.  Additional applications related to fuzing and other high acceleration applications require the clock generators for microelectronics to be survivable and operational under high G environments. Harshness of military environments and application of microelectromechanical systems (MEMS) oscillators is well documented  [1]. Clock oscillators that can deliver high performance (50-100ppb frequency stability over operating temperatures, 1E-11 ADEV), low power, in system programming capability in the range of 1-105MHz are required. The oscillators should be operable under 30kG and survivable under 100kG shocks. Research on quartz crystals has demonstrated g-sensitivity of 2E-69/g [2] and MEMS oscillators have shown even lower sensitivity [3, 4].

 

PHASE I: Conduct a feasibility study and design of a MEMS oscillator with high performance and survivability under high-G conditions, 30kG and 100kG respectively. The consideration for the MEMS design shall be described. Architecture, design and methods of fabrication shall be defended regarding the following application-based specifications:

 

  1. Frequency stability of 100ppb or better in the range of 1-105MHz.
  2. ADEV of 1E-11 in 1 to 9 Sec.
  3. Full in-system programmable for entire range.
  4. The oscillator shall operate over the temperature range (-55 to 105C).
  5. Power consumption <30mW@1.8V
  6. Operation from 1.8V to 3.3V.
  7. Operational under 30kG environment with low G-sensitivity of 0.001ppb/g.
  8. Survivable under 100kG shock.

 

The feasibility study shall detail the process and techniques used along with associated costs. If there are bulk quantity discounts factored in, the report shall disclose quantity price break points and which steps were discounted wherever relevant. It must include:

 

  1. Proposed manufacturing processes flow and techniques used including dicing and etching methodologies, along with figures and diagrams describing the process.
  2. Bulk material and specification (i.e., crystal orientation, dopant species, resistivity, epi thickness, if any, etc.).
  3. Cost break down for manufacturing compared to existing (both commercial and research) and comparative theoretical options. 
  4. Methodologies and analysis techniques used for characterizing the proposed device.

 

The delivered report shall fully describe the proposed techniques and characterization methodologies, including a notional list of fabrication tools, facility requirements, and a program plan for follow-on phase development. If any of the above items cannot be fully addressed, the report must include relevant research and rationale that demonstrates their inapplicability to the proposed technique. If adhering to the above items is possible, but not financially feasible, the report must include relevant justification. Finally, the challenges and special considerations for testing of accelerometers under high-g stress environments shall be addressed.

 

FEASIBILITY DOCUMENTATION: Offerors interested in participating in Direct to Phase II must include in their response to this topic Phase I feasibility documentation that substantiates the scientific and technical merit and Phase I feasibility described in Phase I above has been met (i.e., the small business must have performed Phase I-type research and development related to the topic, but from non-SBIR funding sources) and describes the potential commercialization applications. The documentation provided must validate that the proposer has completed development of technology as stated in Phase I above. Documentation shall include all relevant information including, but not limited to: technical reports, test data, prototype designs/models, and performance goals/results. Work submitted within the feasibility documentation must have been substantially performed by the offeror and/or the principal investigator (PI).

 

PHASE II: Build, test and deliver a fully functional MEMS oscillator based on the design developed in Phase I. Demonstrate the capability of performance while adhering to the specifications outlined in Phase I. Production yields should be considered to keep costs with commercialization a viable option. The final report shall address manufacturing yield and reflect that the tested prototypes were selected from across multiple lots to demonstrate repeatability and quality with low variation within wafer, wafer to wafer, and lot to lot. If a non-random selection was required to optimize performance, the final report must detail reasoning for using non-random selection and the selection criteria used. 

 

Deliver a detailed final report that documents the cost breakdown per device, manufacturing processes utilized, fabrication toolset required to perform the proposed techniques, all facility requirements, all electrical characterization, and all device design data (Technology Computer Aided Design (TCAD) files, modeling/simulation results, etc.). If there are bulk quantity discounts factored in any of the cost breakdowns, the final report shall disclose quantity price break points and which steps were discounted wherever relevant. The final report shall contain sufficient technical detail such that an entity skilled in semiconductor fabrication can repeat the presented results.

 

PHASE III DUAL USE APPLICATIONS: This technology could be utilized for other DoD and commercial applications where high performance and/or repeated shock events may occur, such as precision SATCOM, GNSS microcircuits, fuzing and munition electronics, flight termination systems, or crash test instrumentation.

 

REFERENCES:

  1. T. G. Brown, “Harsh military environments and microelectromechanical (MEMS) device”, Proceedings of IEEE Sensors, vol 2, 2003 
  2. M Bloch et al, “Acceleration ‘G’ Compensated Quartz Crystal Oscillators”, 2009 IEEE International Frequency Control Symposium Joint with the 22nd European Frequency and Time forum, 2009
  3. Bongsang Kim et al, “MEMS Resonators with extremely low vibration and shock sensitivity”, IEEE Sensors, 2011
  4. Beheshteh Najafabadi, “Study of Acceleration Sensitivity and Nonlinear Behavior in Silicon-based MEMS Resonators”, Doctoral Dissertation, University of Central Florida, 2019

 

KEYWORDS: MEMS, Temperature compensated Crystal Oscillator (TCXO ), Oscillators

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