There are many inventions described and illustrated herein. In one aspect, the present inventions relate to oscillator systems which employ a plurality of microelectromechanical resonating structures, and methods to control and/or operate same. The oscillator systems are configured to provide and/or generate one or more output signals having a predetermined frequency over temperature, for example, (1) an output signal having a substantially stable frequency over a given/predetermined range of operating temperatures, (2) an output signal having a frequency that is dependent on the operating temperature from which the operating temperature may be determined (for example, an estimated operating temperature based on a empirical data and/or a mathematical relationship), and/or (3) an output signal that is relatively stable over a range of temperatures (for example, a predetermined operating temperature range) and is “shaped” to have a desired turn-over frequency.

Oscillator system having a plurality of microelectromechanical resonators and method of designing, controlling or operating same

An apparatus and a method for compensating for a mismatch in temperature coefficients of two oscillator frequencies to match a desired frequency ratio between the two oscillator frequencies over a temperature range. In one embodiment of a temperature sensor, first and second oscillators of different temperature characteristics are coupled to a differential frequency discriminator (DFD) circuit. The DFD circuit compensates for the different characteristics in order to match a frequency difference between the first and second frequencies over a temperature range.

Highly accurate temperature stable clock based on differential frequency discrimination of oscillators

A hybrid system having a non-MEMS device and a MEMS device is described. The apparatus includes a non-MEMS device and an integrated circuit including a MEMS device, the integrated circuit formed on a substrate. The integrated circuit includes a control circuit for the non-MEMS device and a MEMS control circuit for the MEMS device.

Hybrid system having a non-MEMS device and a MEMS device

Vibration causes mechanical distortions in optical fibers that induce phase fluctuations in the transmitted optical signal. Information encoded on the optical signal by modulation, such as in a radio-frequency (RF)-photonic link also degrades. A feed-forward correction technique is described that enables 20 dB or more cancellation of vibration-induced phase fluctuations in an optical fiber wound on a spool. The scheme is also applied to an optoelectronic oscillator (OEO). The OEO has emerged as an excellent low-noise source that rivals the best electronic RF oscillators over a broad range of offset frequencies. However, close-to-carrier spectral purity of an OEO is degraded mostly by the vibration-induced phase fluctuations in optical fibers when the temperature is held constant. Implementation of feed-forward phase correction in an OEO has shown improvement by almost an order of magnitude in the vibration sensitivity of the oscillator.

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Cancellation of Vibration-Induced Phase Noise in Optical Fibers

A voltage controlled crystal oscillator (VCXO) is locked to a MEMS oscillator with a variable frequency ratio that is a function of a sensed temperature. That allows the long-term stability of the MEMS oscillator and temperature compensation to be reflected in a VCXO output signal having good short-term stability.

Mems stabilized oscillator

An oscillator and a method for producing an improved oscillator that will generate an accurate frequency when encountering a vibration. The oscillator and method uses a crystal with minimal cross-axis coupling. Further, a first accelerometer produced using MEMS technology is used. The first accelerometer is positioned inside of the oscillator so that the accelerometer accurately measures any vibration encountered by the oscillator. The first accelerometer and the crystal are maintained at constant temperature to minimize phase shifts and gain variations.

Charles Stone

Papers

Method for achieving highly reproducible acceleration insensitive quartz crystal oscillators