353 results about "Differential capacitance" patented technology

Partial fill of an electrochemical test strip is determined by making a DC determination of double layer capacitance from charging or discharging charge on a test strip containing sample, for example a blood sample to be tested for glucose. The measured double layer capacitance is compared to a reference value. The double layer capacitance may be determined as an integral or differential capacitance. Double layer capacitance may also be used for quality control to monitor the quality of electrode formation, particularly in strips using screen printed electrodes.

A touch sensor is provided. The touch sensor includes at least two capacitive sensing electrodes, each of the at least two capacitive sensing electrodes having a surface area that is smaller than an area of a touch from a user. The at least two capacitive sensing electrodes each include a substrate, a single conductive element formed on the substrate, and electronic circuitry coupled to the at least two capacitive sensing electrodes for measuring a self-capacitance of the at least two capacitive sensing electrodes. A position corresponding to the touch of a user is determined by the electronic circuitry based on a difference of the measured self-capacitance between the at least two capacitive sensing electrodes.

A circuit and method are given, which realizes a stable yet sensitive differential capacitance measuring device with good RF-suppression and with very acceptable noise features for use in capacitive sensor evaluation systems. By evaluating the difference of capacitor values only—with the help of a switched capacitor front-end—large spreads of transducer capacitor values are tolerable. Furthermore a mode of operation can be set up, where no essential galvanic connection between sensor input and the active read-out input at any given time is existing. The solution found exhibits a highly symmetrical construction. Using the intrinsic advantages of that solution the circuit of the invention is manufactured as an integrated circuit with standard CMOS technology at low cost.

A detection circuit is provided with a differential capacitive sensor and with an interface circuit having a first sense input and a second sense input, electrically connected to the differential capacitive sensor. Provided in the interface circuit are: a sense amplifier connected at input to the first sense input and to the second sense input and supplying an output signal related to a capacitive unbalancing of the differential capacitive sensor; and a common-mode control circuit, connected to the first sense input and to the second sense input and configured to control a common-mode electrical quantity present on the first sense input and on the second sense input. The common-mode control circuit is of a totally passive type and is provided with a capacitive circuit, which is substantially identical to an equivalent electrical circuit of the differential capacitive sensor and is driven with a driving signal in phase opposition with respect to a read signal supplied to the differential capacitive sensor.

A coupled winding cancels parasitic inductance of first and second capacitors. In an EMI filter having common mode capacitors and a differential capacitors, first and second windings cancel parasitic inductance of the common mode and differential capacitors.

A CMOS compatible silicon differential condenser microphone and a method for manufacturing the same are provided. The microphone(1000) comprises a silicon substrate(100), wherein a CMOS circuitry is accommodated thereon; a first rigid conductive perforated backplate(200) supported on the silicon substrate with an insulating layer(120) inserted therebetween; a second rigid perforated backplate(400) formed above the first backplate, including CMOS passivation layers(400a, 400c) and a metal layer(400b) sandwiched between the CMOS passivation layers as an electrode plate of the second plate, wherein an air gap, with a spacer forming its boundary, is provided between the opposite perforated areas of the first backplate and the second backplate; a compliant diaphragm(300) provided between the first backplate and the second backplate, wherein a back hole(150) is formed to be open in the silicon substrate underneath the first backplate so as to allow sound pass through, and the diaphragm and the first backplate form a first variable condenser, the diaphragm and the second backplate form a second variable condenser, and the first variable condenser and the second variable condenser form differential condensers.

A method for enhancing the linearity of a differential capacitive sensor as a function of beam displacement. An ac-modulated feedback connection from a sensor output terminal to a movable beam electrode is provided through a fix-up capacitor. The output terminal signal is inverted in the feedback connection so that the fix-up capacitor reduces the capacitance from the fixed electrodes to the beam electrode. When the fix-up capacitor value is chosen approximately equal to the fixed capacitance of the differential capacitor, the feedback circuit compensates for the effect of this fixed capacitance. The linearity of the output as a function of the displacement of the beam is improved. Thus, the signal-to-noise ratio of devices such as accelerometers may be increased by allowing sensors to employ a large displacement range. The invention may be used in differential accelerometers and in other types of differential capacitive sensors.

Programmable differential capacitance is implemented in equalization circuits. The programmable differential capacitance improves the common mode rejection ratio of circuits processing differential signals of various frequencies and voltage swings. Multiple capacitance devices provide the programmable capacitance, which provides an equalization circuit with different, selectable (i.e., programmable) values of capacitance for boosting the transition speed and strength of differential signals processed by the equalization circuit.

A capacitive pressure sensor includes a electrically conductive, generally piston shaped diaphragm with a flexible base wall configured to deflect under pressure. The diaphragm is generally U-shaped in cross section. The base wall includes an upper, flat sensing surface which acts as a capacitive electrode. The diaphragm further includes a step around a radially-outermost perimeter which is elevated from the flat sensing surface. A sensing electrode body is located on top of the step and creates a capacitive sensing cavity between the sensing surface and the bottom surface of the electrode body. On the bottom surface of the electrode body is formed a center, circular electrode and a ring electrode that surrounds the center electrode. The center electrode and the sensing surface form a variable capacitor which changes with pressure and the ring electrode and the sensing surface form a reference capacitor. A circuit determines a differential capacitance between the variable capacitor and the reference capacitor and generates a pressure signal indicative of the fluid pressure applied to the diaphragm. A spring ring holds the sensing electrode body against the diaphragm when assembled. The diaphragm can be a machined metal part or a sheet metal cup. The sensing electrodes and signal generating circuit can take the form of a hybrid circuit.

The invention provides a micro-electromechanical system (MEMS) triaxial accelerometer and a manufacturing method thereof. The MEMS triaxial accelerometer comprises a sensitive device layer, an upper cover board layer and a lower supporting body layer, wherein clearances are reserved between the sensitive device layer and the upper cover board layer as well as between the sensitive device layer and the lower supporting body layer; the sensitive device layer comprises a supporting frame body, an elastic beam, three independent sensitive mass blocks, movable comb teeth, fixed comb teeth and an electrode; the three independent sensitive mass blocks in the sensitive device layer are used for detecting acceleration signals of three axes X, Y and Z respectively; an acceleration sensor in each direction is hung in the supporting frame body through the corresponding sensitive mass block by the elastic beam which is only sensitive to the detection direction; a plurality of pairs of movable comb teeth are formed on each sensitive mass block by using a body silicon processing technology; a plurality of pairs of fixed comb teeth are correspondingly formed on the supporting frame body to form a pair of differential capacitors serving as sensitive capacitors; and the differential comb tooth capacitors in different directions generate a differential capacitance change in response to the acceleration signals in the corresponding directions.

Partial fill of an electrochemical test strip is determined by making a DC determination of double layer capacitance from charging or discharging charge on a test strip containing sample, for example a blood sample to be tested for glucose. The measured double layer capacitance is compared to a reference value. The double layer capacitance may be determined as an integral or differential capacitance. Double layer capacitance may also be used for quality control to monitor the quality of electrode formation, particularly in strips using screen printed electrodes.

A MEMS pressure sensor device is provided that can provide both a linear output with regard to external pressure, and a differential capacitance output so as to improve the signal amplitude level. These benefits are provided through use of a rotating proof mass that generates capacitive output from electrodes configured at both ends of the rotating proof mass. Sensor output can then be generated using a difference between the capacitances generated from the ends of the rotating proof mass. An additional benefit of such a configuration is that the differential capacitance output changes in a more linear fashion with respect to external pressure changes than does a capacitive output from traditional MEMS pressure sensors.

Methods of measuring displacement of a movable mass in a microelectromechanical system (MEMS) include driving the mass against two displacement-stopping surfaces and measuring corresponding differential capacitances of sensing capacitors such as combs. A MEMS device having displacement-stopping surfaces is described. Such a MEMS device can be used in a method of measuring properties of an atomic force microscope (AFM) having a cantilever and a deflection sensor, or in a temperature sensor having a displacement-sensing unit for sensing a movable mass permitted to vibrate along a displacement axis. A motion-measuring device can include pairs of accelerometers and gyroscopes driven 90° out of phase.

A differential capacitor one terminal capacitor interface circuit for sensing the capacitance of first and second capacitors includes a differential integrating amplifier having first and second summing nodes and an input common mode voltage; and a switching circuit for charging a first capacitor of said differential one terminal capacitor to a first voltage level and a second capacitor of said differential one terminal capacitor to a second voltage level in a first phase, in a second phase connecting said first capacitor to said first summing node and said second capacitor to said second summing node of said amplifier to provide first and second output changes substantially representative of the difference between said first and second voltage levels and said input common mode voltage, in a third phase charging said first capacitor to said second voltage level and said second capacitor to said first voltage level, and in a fourth phase connecting said first capacitor to said second summing node and said second capacitor to said first summing node of said amplifier to provide third and fourth output changes substantially representative of the difference between said first and second voltage levels and said input common mode voltage, the combined first, second, third and fourth changes representing the capacitance of said first and second capacitors substantially independent of said input common mode voltage.

A system and method for measuring capacitance of a capacitive sensor array is disclosed. Upon measuring the capacitance, position information with respect to the sensor array may be determined. A column, a first row, and a second row of a capacitive sensor array may be selected. The first row and the second row intersect with the column of the capacitive sensor array. A differential capacitance between the first row and the second row may be measured. The differential capacitance may be utilized in determining a location of an object proximate to the capacitive sensor array.

The invention discloses a high accuracy capacitive readout circuit with temperature compensation, belonging to the design field of integrated circuits. The circuit realizes high accuracy capacitive readout owing to the adoption of a chopping modulation technology, and can simultaneously realize temperature compensation by adjusting temperature characteristics of internal voltage reference. The circuit comprises an oscillator, a voltage reference source, a full-differential operational amplification unit, a common-mode operational amplification unit, a low pass filter, a switch device and a digital circuit. The voltage reference source generates a square wave in cooperation with a single-pole double throw switch, and the square wave is applied to an intermediate polar plate of a differential capacitance to be detected in order to implement modulation. The full-differential operational amplification unit and a feedback capacitance constitute a charge integrator to detect a transfer charge formed by the variation of the capacitance to be detected. Demodulation is realized by the switch device and the low pass filter. Both an input end and an output end of the full-differential operational amplification unit are set through a switch cycle. The common-mode operational amplification unit and the feedback capacitance constitute a common-mode feedback loop which is connected with the input end of the full-differential operational amplification unit to play the role of inputting common-mode voltage stably.

The invention relates to a micro machine differential capacitance accelerometer with a symmetrical structure, which is connected with a movable silicon structure component through an anchoring area along the upper direction and the lower direction. Elastic supporting beams of the silicon structure component are divided into an upper layer and a lower layer and distributed between a movable mass block and a fixedly supported frame as well as connected with the movable mass block and the fixedly supported frame; and the round angle transition is adopted at joints of the movable mass block and the fixedly supported frame as well as the beams; both the upper surface and the lower surface of the movable mass block are provided with gas flow guide grooves; and an electrode cover plate can be made of a silicon material. The gas flow guide grooves distributed on both the upper surface and the lower surface of the mass block are beneficial to regulating the squeeze-film damping effect of the accelerometer so as to structurally improve the dynamic characteristic of the surface separated capacitance detection accelerometer. A plurality of the elastic supporting beams of the accelerometer are made of single crystal silicon materials with a single doping concentration, thereby eliminating thermal inconsistency stress caused by adopting different materials and the thermal inconsistency stress caused by different single crystal silicon doping concentrations.

The invention belongs to the technical field of micro-electro mechanic systems (MEMS), and relates to a piezoelectricity driven capacitance detecting two-axis gyroscope. According to the invention, a lower surface of a gyroscope oscillator with a shape of a round disc, a wheel spoke or a honeycomb is connected to a supporting cylinder. The other end of the supporting cylinder is fixed on a lower pole plate. The lower pole plate is fixed on a carrier. An upper pole plate signal detecting electrode is positioned on a lower end surface of the upper pole plate. A lower pole plate signal detectingelectrode is positioned on an upper end surface of the lower pole plate. The upper pole plate, the lower pole plate and the gyroscope oscillator are assembled, and differential capacitance is formed for detecting output signals. According to the invention, a special modality of a round disc, a wheel spoke or a honeycomb shape is adopted in the gyroscope oscillator, the detection is driven by piezoelectricity effect, and the detection is carried out by using capacitance. Therefore, angular velocities parallel to the upper and the lower surfaces of the gyroscope oscillator can be sensitively detected. According to the invention, with an MEMS micromachining technology, two-axis detection can be realized, the machining technology is easy to realize, the reliability is high, the energy consumption is low, the impact resistance is high, and the gyroscope can operate well in severe environments.

This invention relates to weak signal test technology, specifically it is a kind of difference capacitance sensor test circuit. It solves the problem that the test precision of the exist difference capacitance sensor test circuit is not high, includes the full wave rectifying circuit, the said full wave rectifying circuit includes the integrated amplification circuit U1B and dynatron Q1, the phase reversal end of the integrated amplification U1B links with the output end out2 of the summator by the resistance R21, the in-phase end links with the output end out2 of the summator by the resistance R19,R20, the resistance R22 is set between the phase reversal end and the output end, the connection node of the resistance R19,R20 connects the collector electrode of the dynatron Q1, the base electrode of the dynatron Q1 links with the output end out1 of the waveform generator by the resistance R17, R18, the connection node of the resistance R17, R18 earth by the diode D3. The structure of the invention is in reason, the test precision of the weak signal produced by the difference capacitance sensor, the reliability is high.

The invention discloses a pseudo-differential capacitive successive approximation register analog-digital converter. The analog-digital converter comprises a first capacitor array, a second capacitor array, a calibration capacitor array and a comparator, wherein lower-bit-segment sub-capacitor arrays of the first capacitor array keep single-end structures; a higher-bit first-segment sub-capacitor array of the first capacitor array and the second capacitor array construct a differential structure; and the first capacitor array and the second capacitor array construct a pseudo-differential capacitor array in which single ends are combined with the differential structure. In an analog-digital conversion process, a transition code value is formed after completion of a least-significant differential weight bit, thereby realizing differential-single end transition. An output end of the calibration capacitor array is connected with an output end of the second capacitor array through a coupling capacitor, and the calibration capacitor array is used for calibrating mismatch of capacitors in the pseudo-differential capacitor array and the offset of the comparator. Through adoption of the analog-digital converter, the chip area can be saved; self-calibration can be performed; and the conversion accuracy is increased.

A capacitance readout circuit for secondary summation of cross-sampling charge, which is a symmetrical circuit structure, including switches 1, 2, 5, 6 for charging the sensor capacitance, reference capacitor arrays CR1 and CR2, and for charging the reference Switches 3, 4, 7, 8 for charging the capacitor array, switches 9, 10, 11, 12, 13, 14, 15, 18 for charge transfer, capacitors CD1 and CD2 for offset cancellation and low frequency noise suppression, and The switches 16 and 17 that provide the DC operating point for the circuit, the fully differential transconductance operational amplifier, the integrating capacitors CI1 and CI2 for storing the transferred charges, the integrating capacitors CI3, CI4 and switches 22 and 23 for adjusting the circuit gain, and the For the switches 19, 20, 21, 24 that provide DC bias for the fully differential transconductance inputs, the entire readout circuit is controlled by a 4-phase non-overlapping clock circuit.

The invention belongs to the field of a micro electro mechanical system, relating to a four-folding beam variable area differential capacitance structure micro-acceleration sensor and a manufacture method thereof. The sensor consists of a movable mass block, paired spring folding beams, an inserting finger-shaped lower electrode and a micro-acceleration sensor outer frame, wherein the front end and the back end of the movable mass block are connected with the acceleration sensor outer frame through the spring folding beams on the action direction of the outer load; the movable mass block, the spring folding beams and the acceleration sensor outer frame are formed into an integral structure; the lower surface of the movable mass block is provided with an upper electrode; a certain gap is formed between the upper electrode and the inserting finger-shaped lower electrode to be formed into a plate differential capacitor; and the upper electrode is boned with the inserting finger-shaped lower electrode through the acceleration sensor outer frame. With the structure, the invention obviously solves the problem of the nonlinearity of the existing variable gap structure, is good for manufacturing follow-up detecting circuits, leads a vibration mode to be better separated, improves the anti-jamming capability of a device, and increases the sensitivity of the sensor.

The invention provides a frame structure differential capacity type speed-up sensor. It etches bonding needed table on the back of the silicon sheet; the glass base sheet forms a fixed block with the bonding needed table; it etches an elastic beam, a quality block and fixed and active electrode pictures, wherein the bonding block comprises upper, lower, left, right and inner bonding blocks; the upper and lower bonding blocks are connected with the elastic beam; the frame sharp quality block is between the two elastic beams; the inner side of the left and right bonding blocks and the two sides of the middle bonding block have fixed electrode; the frame sharp quality block has an active electrode which is matched with the fixed electrode. The upper and lower bonding blocks and each bonding block connected with the fixed electrode use the electrostatic bonding to fix it on the glass base sheet.

The present invention discloses an ultra short baseline extensometer, which relates to an extensometer. The present invention has the structure that one end of a baseline bar (130) is connected with a displacement sensor (110), which is connected with a first base rock (310) through a nulling device (120); the other end of the baseline bar (130) is connected with a calibrater (150) and then connected with a second base rock (320) through a fixed end (160); the displacement sensor (110) is respectively connected with a measurement and control system (200) through the calibrater (150); the displacement sensor (110) is a differential capacitance sensor (211) with an entire seal structure. The baseline of the present invention is not more than 100 cm, the resolving ability is superior to 1 is multiplied by 10 and then minus 10, the mechanical drive does not exist, the calibration is reliable; the extensometer can be arranged vertically; the volume is small, thus the extensometer is suitable for carrying, and adaptable to the flow of the forerunning effect of earthquake and the emergency monitoring; and the extensometer can be generalized to be used on a long baseline extensometer and other micro-displacement measuring devices.

The invention discloses a differential-capacitive type mems accelerometer, which belongs to the inertia sensor field of a micro electric system (MEMS). The accelerometer comprises a sensitive quality component which is composed of a silicon chip, an insulating layer, and movable electrodes, fixing electrodes, a base piece, and a folding beam. The movable electrodes are distributed in equal distance on the silicon chip, the insulating layer is used to separate each movable electrode in space, the folding beam is arranged on two ends of the sensitive quality component and is fixed on the base plate through a vertical prop, thereby whole surfaces of the movable electrodes are pending and in parallel, the fixing electrodes are distributed in equal distance on the base plate and are arranged crisscross with the movable electrodes to form a group of differential-capacitive capacitances. The invention increases greatly sensitive quality of a quality block, thereby sensitivity and distinguish ability are increased greatly. The invention has simple structure, and uses integrated circuit plane manufacturing technique to process the movable electrodes and the fixing electrodes. The invention has low cost, simple manufacturing technique, high reproducibility, and high rate of finished products, and is easy to be produced in batches.

The invention discloses an MDOF (multi-degree of freedom) differential capacitance displacement sensor calibration device. The device comprises a differential capacitance displacement sensing module, a laser interferometry ranging module, a temperature control module and a data processing module, wherein the differential capacitance displacement sensing module comprises a mechanical sensitive probe and a differential capacitance sensing circuit; the mechanical sensitive probe comprises a movable polar plate, an MDOF micrometric displacement table, fixed polar plates and an insulating base; the laser interferometry ranging module comprises a laser, a shielding frame and N interference fringe units distributed in the translation DOF direction; the temperature control module is used for shielding disturbance of outside environment temperature; the laser interferometry ranging module measures displacement of the movable polar plate relative to the fixed polar plates, the differential capacitance displacement sensing module outputs a voltage signal, and a data acquisition and processing system processes data to obtain a scale coefficient when the movable polar plate moves to output voltage of the differential capacitance displacement sensing module in a translation DOF manner, so that the resolution level of the high-precision differential capacitance displacement sensing module with a micron-dimension range is accurately evaluated.

An operational transconductance amplifier includes a cascode differential-pair amplifying circuit, a bias driving circuit, and a common mode feedback circuit. The cascode differential-pair amplifying circuit is configured for receiving a differential input voltage and for providing a differential output voltage. The bias driving circuit is configured for providing a first bias current to drive the cascode differential-pair amplifying circuit and for adjusting the transconductance of the transconductance amplifier. The bias driving circuit includes a first floating-gate transistor. The first floating-gate transistor is configured for adjusting the first bias current. The common mode feedback circuit is configured for adjusting a second bias current of the cascode differential-pair amplifying circuit according to the differential output voltage so that the differential output voltage is stabilized. A reconfigurable fully differential voltage sensing amplifier and a reconfigurable fully differential capacitive sensing amplifier are disclosed herein as well.