Abstract: A pressure/vacuum sensor and method, comprising: driving a MEMS piezoresistive resonator (8) into resonant vibration, applying Joule heating to the resonator (8); and sensing a variable parameter that varies in response to the tendency of the resonant frequency (fo) to depend upon the temperature of the resonator (8), the temperature thereof depending upon the pressure. The variable parameter may be the resonant frequency of the resonator (8), or a change therein, or may be derived from a feedback loop, being for example a time integrated feedback signal (82) or a reading (94) of the sense current (22), the loop keeping the resonant frequency constant in opposition to the above mentioned tendency. A reference MEMS capacitive resonator (62) may be located in the vicinity of the resonator (8) for compensating purposes.

Abstract: A novel Si MEMS piezoresistive resonator is described. The resonator has a shape of a frame, such as a ring or a polygon frame, which has two or more anchors. Electrodes located at the outer or inner rim of the resonant structure are used to excite the structure electrostatically into resonance with a desired mode shape. One or plurality of locally doped regions on the structure is used for piezoresistive readout of the signal. In the most preferred embodiments, the structure is a ring, which has four anchors, two electrodes and four piezoresistive regions at different segments of the structure. The piezoresistive regions are alternatively located at the outer rim and inner rim of the structure in such a way that the piezoresistive signals of the same sign from different regions can be collected. Advantages of this device are large readout signal, large electrode area, robustness, suppressed out-of-plane vibration and larger usable linear range.

Abstract: The present invention relates to a method of forming a micro cavity having a micro electrical mechanical system (MEMS) in a process, such as a CMOS process. MEMS resonators are being intensively studied in many research groups and some first products have recently been released. This type of device offers a high Q-factor, small size, high level of integration and potentially low cost. These devices are expected to replace bulky quartz crystals in high-precision oscillators and may also be used as RF filters. The oscillators can be used in time-keeping and frequency reference applications such as RF modules in mobile phones, devices containing blue-tooth modules and other digital and telecommunication devices.

Abstract: A method of operating a micro-electromechanical system, comprising a resonator; an actuation electrode; and a first detection electrode, to filter and mix a plurality of signals. The method comprises applying a first alternating voltage signal to the actuation electrode, wherein an actuation force is generated having a frequency bandwidth that is greater than and includes a resonant bandwidth of a mechanical frequency response of the resonator, and wherein a displacement of the resonator is produced which is filtered by the mechanical frequency response and varies a value of an electrical characteristic of the first detection electrode. The method also comprises applying a second alternating voltage signal to the first detection electrode, wherein the second voltage signal is mixed with the varying value to produce a first alternating current signal. The first alternating current signal is detected at the first detection electrode.

Abstract: An RF MEMS device comprising one or more free-standing thin films configured for motion in response to actuation or stimulation, the one or more thin films comprising an alloy of aluminum and magnesium, and optionally one or more further materials. The resultant thin film has improved hardness and reduced creep relative to conventional thin films.

Abstract: A resonator comprises a resonator mass (34), a first connector (30) on a first side of the mass connected between the resonator mass and a first fixed mounting and a second connector (32) on a second, opposite, side of the mass connected between the resonator mass and a second fixed mounting. Drive means drives the mass (34) into a resonant mode in which it oscillates in a sideways direction, thereby compressing one of the first and second connectors while extending the other of the first and second connectors.

Abstract: A tuneable capacitor arrangement for RF use has two series coupled MEMS variable capacitors (C1,C2;C4,C5,C6,C7), varied according to a control signal. The series coupling enables the capacitor to withstand a higher voltage since this is shared by the individual capacitors in a series coupled arrangement. An increase in size of electrodes for each capacitor is compensated by a reduction in size of the springs supporting movable electrodes. These springs can have a larger stiffness value since the capacitance is larger. This means shorter springs, which can also result in a reduction in problems of stiction, resistance, and slow switching. The capacitances have a fixed and a movable electrode, with the RF signal coupled to the fixed electrode to avoid the springs needing to carry an RF signal. This can reduce the problems of inductance and resistance in the springs.

Abstract: The invention relates to a MEMS resonator comprising a first electrode, a movable element (48) comprising a second electrode, the movable element (48) at least being movable towards the first electrode, the first electrode and the movable element (48) being separated by a gap (46, 47) having sidewalls. According to the invention, the MEMS resonator is characterized in that the gap (46, 47) has been provided with a dielectric layer (60) on at least one of the sidewalls.

Abstract: A novel Si MEMS piezoresistive resonator is described. The resonator has a shape of a frame, such as a ring or a polygon frame, which has two or more anchors. Electrodes located at the outer or inner rim of the resonant structure are used to excite the structure electrostatically into resonance with a desired mode shape. One or plurality of locally doped regions on the structure is used for piezoresistive readout of the signal. In the most preferred embodiments, the structure is a ring, which has four anchors, two electrodes and four piezoresistive regions at different segments of the structure. The piezoresistive regions are alternatively located at the outer rim and inner rim of the structure in such a way that the piezoresistive signals of the same sign from different regions can be collected. Advantages of this device are large readout signal, large electrode area, robustness, suppressed out-of-plane vibration and larger usable linear range.

Abstract: A method of operating a micro-electromechanical system, comprising a resonator; an actuation electrode; and a first detection electrode, to filter and mix a plurality of signals. The method comprises applying a first alternating voltage signal to the actuation electrode, wherein an actuation force is generated having a frequency bandwidth that is greater than and includes a resonant bandwidth of a mechanical frequency response of the resonator, and wherein a displacement of the resonator is produced which is filtered by the mechanical frequency response and varies a value of an electrical characteristic of the first detection electrode. The method also comprises applying a second alternating voltage signal to the first detection electrode, wherein the second voltage signal is mixed with the varying value to produce a first alternating current signal. The first alternating current signal is detected at the first detection electrode.

Abstract: The invention relates to a MEMS resonator comprising a movable element (48), the movable element (48) comprising a first part (A) having a first Young's modulus and a first temperature coefficient of the first Young's modulus, and the movable element (48) further comprising a second part (B) having a second Young's modulus and a second temperature coefficient of the second.

Abstract: A resonator comprises a resonator mass (34), a first connector (30) on a first side of the mass connected between the resonator mass and a first fixed mounting and a second connector (32) on a second, opposite, side of the mass connected between the resonator mass and a second fixed mounting. Drive means drives the mass (34) into a resonant mode in which it oscillates in a sideways direction, thereby compressing one of the first and second connectors while extending the other of the first and second connectors.

Abstract: The present invention relates to a method of forming a micro cavity having a micro electrical mechanical system (MEMS) in a process, such as a CMOS process. MEMS resonators are being intensively studied in many research groups and some first products have recently been released. This type of device offers a high Q-factor, small size, high level of integration and potentially low cost. These devices are expected to replace bulky quartz crystals in high-precision oscillators and may also be used as RF filters.

Abstract: An RF MEMS device comprising one or more free-standing thin films configured for motion in response to actuation or stimulation, the one or more thin films comprising an alloy of aluminum and magnesium, and optionally one or more further materials. The resultant thin film has improved hardness and reduced creep relative to conventional thin films.

Abstract: A pressure/vacuum sensor and method, comprising: driving a MEMS piezoresistive resonator (8) into resonant vibration, applying Joule heating to the resonator (8); and sensing a variable parameter that varies in response to the tendency of the resonant frequency (fo) to depend upon the temperature of the resonator (8), the temperature thereof depending upon the pressure. The variable parameter may be the resonant frequency of the resonator (8), or a change therein, or may be derived from a feedback loop, being for example a time integrated feedback signal (82) or a reading (94) of the sense current (22), the loop keeping the resonant frequency constant in opposition to the above mentioned tendency. A reference MEMS capacitive resonator (62) may be located in the vicinity of the resonator (8) for compensating purposes.

Abstract: A tuneable capacitor arrangement for RF use has two series coupled MEMS variable capacitors (C1,C2;C4,C5,C6,C7), varied according to a control signal. The series coupling enables the capacitor to withstand a higher voltage since this is shared by the individual capacitors in a series coupled arrangement. An increase in size of electrodes for each capacitor is compensated by a reduction in size of the springs supporting movable electrodes. These springs can have a larger stiffness value since the capacitance is larger. This means shorter springs, which can also result in a reduction in problems of stiction, resistance, and slow switching. The capacitances have a fixed and a movable electrode, with the RF signal coupled to the fixed electrode to avoid the springs needing to carry an RF signal. This can reduce the problems of inductance and resistance in the springs.

Abstract: The invention relates to a MEMS resonator comprising a movable element (48), the movable element (48) comprising a first part (A) having a first Young's modulus and a first temperature coefficient of the first Young's modulus, and the movable element (48) further comprising a second part (H) having a second Young's modulus and a second temperature coefficient of the second.

Abstract: The invention relates to a MEMS resonator comprising a first electrode, a movable element (48) comprising a second electrode, the movable element (48) at least being movable towards the first electrode, the first electrode and the movable element (48) being separated by a gap (46, 47) having sidewalls. According to the invention, the MEMS resonator is characterized in that the gap (46, 47) has been provided with a dielectric layer (60) on at least one of the sidewalls.