Patents Assigned to SiTime Inc.
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Patent number: 7545238Abstract: One embodiment of the present invention sets forth a serrated tooth actuator for driving MEMS resonator structures. The actuator includes a fixed drive electrode having a serrated tooth surface opposing a MEMS resonator arm also having a serrated tooth surface, where the MEMS resonator arm is configured to rotate towards the drive electrode when an AC signal is applied to the drive electrode. Such a configuration permits higher amplitude signals to be applied to the drive electrode without the performance of the actuator being compromised by nonlinear effects. In addition, the serrated tooth configuration enables a sufficiently high actuating force to be maintained even though the distance traversed by the MEMS resonator arm during operation is quite small. Further, the serrated configuration allows a MEMS resonator system to withstand larger fluctuations in voltage and larger substrate stresses without experiencing a substantial shift in resonant frequency.Type: GrantFiled: December 20, 2006Date of Patent: June 9, 2009Assignee: SiTime Inc.Inventors: Paul Merritt Hagelin, David Raymond Pedersen
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Patent number: 7544531Abstract: To suppress stiction of a MEMS resonator during fabrication, conductive structures of the MEMS resonator are electrically coupled via a ground strap during the step of forming isolation trenches around their contact structures. After the isolation trenches have been formed, the ground strap is transformed into a non-conductive material to complete the electrical isolation of the conductive structures. An etch mask formed on top of the ground strap prevents etching of the ground strap during the formation of the trenches. Depending on the etching process, the ground strap may be formed as a bridge that suspends above the isolation trench or as a column that extends down to the bottom of the isolation trench.Type: GrantFiled: June 28, 2007Date of Patent: June 9, 2009Assignee: SiTime Inc.Inventor: Charles Grosjean
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Patent number: 7545228Abstract: A method for generating a temperature-compensated timing signal that includes counting, within an update interval, a first number of oscillations of a first micro-electromechanical (MEMS) resonator, a second number of oscillations of a second MEMS resonator and a third number of oscillations of a digitally controlled oscillator (DCO), computing a target DCO count based on the first number and second number of oscillations, computing a loop error signal based on the target DCO count and the third number of oscillations, and modifying an output frequency of a temperature-dependent (DCO) timing signal based on the loop error signal. The duration of the update interval may also be modified based on temperature conditions, and the update interval may also be interrupted and the output frequency immediately adjusted, if a significant temperature change is detected. Thus, dynamic and precise temperature compensation is achieved that accommodates constant, slowly changing, and rapidly changing temperature conditions.Type: GrantFiled: September 12, 2007Date of Patent: June 9, 2009Assignee: SiTime Inc.Inventors: Crist Lu, Erno Klaassen, Sathi Perumal
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Patent number: 7545237Abstract: One embodiment of the present invention sets forth a serrated tooth actuator for driving MEMS resonator structures. The actuator includes a fixed drive electrode having a serrated tooth surface opposing a MEMS resonator arm also having a serrated tooth surface, where the MEMS resonator arm is configured to rotate towards the drive electrode when an AC signal is applied to the drive electrode. Such a configuration permits higher amplitude signals to be applied to the drive electrode without the performance of the actuator being compromised by nonlinear effects. In addition, the serrated tooth configuration enables a sufficiently high actuating force to be maintained even though the distance traversed by the MEMS resonator arm during operation is quite small. Further, the serrated configuration allows a MEMS resonator system to withstand larger fluctuations in voltage and larger substrate stresses without experiencing a substantial shift in resonant frequency.Type: GrantFiled: December 20, 2006Date of Patent: June 9, 2009Assignee: SiTime Inc.Inventors: Paul Merritt Hagelin, David Raymond Pedersen
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Patent number: 7545239Abstract: One embodiment of the present invention sets forth a serrated tooth actuator for driving MEMS resonator structures. The actuator includes a fixed drive electrode having a serrated tooth surface opposing a MEMS resonator arm also having a serrated tooth surface, where the MEMS resonator arm is configured to rotate towards the drive electrode when an AC signal is applied to the drive electrode. Such a configuration permits higher amplitude signals to be applied to the drive electrode without the performance of the actuator being compromised by nonlinear effects. In addition, the serrated tooth configuration enables a sufficiently high actuating force to be maintained even though the distance traversed by the MEMS resonator arm during operation is quite small. Further, the serrated configuration allows a MEMS resonator system to withstand larger fluctuations in voltage and larger substrate stresses without experiencing a substantial shift in resonant frequency.Type: GrantFiled: December 20, 2006Date of Patent: June 9, 2009Assignee: SiTime Inc.Inventors: Paul Merritt Hagelin, David Raymond Pedersen