413 results about "Instrumentation amplifier" patented technology

A multidrop network of multichannel, addressable sensing modules (ASM's), to be embedded within a composite structure, remotely powered, and interrogated by a personal computer through a non-contacting inductive link. Each ASM contains a microprocessor with non-volatile memory, multiplexer, programmable gain and filter instrumentation amplifier, and sigma delta analog to digital converter (all housed in two thin surface mount packages). An embedded mothernode includes circuitry for power and data reception (into the structure), and data transmission (back out of the structure). The external interrogation system communicates into the network of ASM's by modulating the AC waveform that delivers power to the embedded electronics. Once addressed, each ASM powers up its programmable (gain & filter) sensing channels (3 full differential or 5 pseudo differential) and data conversion elements. Sensed data are pulse code modulated, including error checking, which serially modulate an RF carrier for wireless transmission out of the composite to the interrogating computer. These advanced, micro-miniature sensing networks may be applied to a wide variety of military, medical, & civil structures.

A thermocouple measuring circuit for sensing a temperature at a measuring point is provided. The thermocouple measurement circuit (12) includes a thermocouple input for sensing a temperature at a measuring point, a compensation circuit (14) for compensating thermocouple effects of junctions of the thermocouple, and an instrumentation amplifier (16) for summing an output of the thermocouple and an output of the compensation circuit and outputting a voltage indicative of the temperature sensed, wherein the output of the compensation circuit is a reference voltage for the output of the instrumentation amplifier. Various embodiments of the thermocouple measurement circuit may be employed in electrosurgical generators for controlling output power dependent on temperature conditions.

Chopper stabilized amplifiers combining low clock noise and linear frequency characteristics. The chopper stabilized amplifiers are used in offset correction circuitry, with the output of the chopper stabilized amplifiers being integrated by an integrator. The integrator operates on alternate cycles, with a sample and hold circuit sampling the integrator output when the integrator is not integrating, with the output of the sample and hold being coupled to the main amplification path to cancel offset after at least some amplification is achieved. Autozeroing of amplifiers in the offset correction circuitry is also disclosed. The invention is applicable to operational amplifiers and instrumentation amplifiers.

An electrophysiological sensor, weak electrical signal conditioning circuit and method for controlling the circuit as provided. The sensor includes rigid filiform conducting nanostructures connected to a conducting substrate and operable to penetrate an organic tissue. The circuit includes an instrumentation amplifier with an input connected to a first electrode in contact with a first area of a medium, and a second input; a voltage generating device connected to an electrode in contact with a second area of the medium for applying a continuous reference signal to it; a compensator, electrically insulated from the device, for compensating the direct current offsets of a weak electrical signal received by the first electrode, generating a signal with a reference voltage with a value which can be modified by a control system, and supplying it to the second input. A method is also provided for controlling the circuit.

An apparatus and method make use of a single shunt and two or more instrumentation amplifiers, switchably measuring voltages at the shunt. This permits current measurement. At times each instrumentation amplifier has its input shorted, which permits zeroing out many sources of offset in the signal path of that amplifier. Dynamic range is several orders of magnitude better than known current measurement approaches, permitting coulometry.

The invention provides a wide-range broadband current sensor base on a tunnel magnetic resistance effect, and belongs to the field of sensing measurement. The sensor comprises an open magnet ring, current sensing chips, a compensation coil, a sampling resistor, an instrument amplifier, a zeroing circuit, a current output module and a power supply module; the current sensing chips include a high-sensitivity TMR sensing chip and a low-sensitivity TMR sensing chip, and are provided with two current measuring output points; the open magnet ring sleeves a current carrying lead, so that the current carrying lead penetrates through an inner hole of the open magnet ring; the compensation coil is wound around the open magnet ring; the high-sensitivity TMR sensing chip is arranged in an open air gap position of the open magnet ring; the low-sensitivity TMR sensing chip is arranged outside the open magnet ring; the high-sensitivity TMR sensing chip with other composition parts forms a closed loop structure; and the low-sensitivity TMR sensing chip, the instrument amplifier and the zeroing circuit form an open loop structure. The current sensor has the advantages of being wide in measuring range, wide in frequency band, small in size, high in precision, low in cost, free of intrusion and convenient to install and maintain.

Fast-settling capacitive-coupled amplifiers are disclosed. The amplifiers use two Capacitive Coupled paths embedded in a Multipath Hybrid Nested Miller Compensation topology. One path is a direct high frequency path and the other path is a slower stabilization path. This combination results in a flat frequency response to and through the chopper frequency, and a fast settling response. Various exemplary embodiments are disclosed, including operational amplifier and instrumentation amplifier configurations.

An overcurrent detection circuit includes a current detection resistor that generates a voltage in proportion to current flowing through a switching element and a comparator that compares the voltage detected via the current detection resistor and a reference voltage generated by a reference voltage generation circuit to thereby detect overcurrent flowing through the switching element. In particular, the reference voltage generation circuit includes: a first resistance voltage dividing circuit that resistance-divides a standard voltage by connecting, in series, two types of resistors having different temperature characteristics; a second resistance voltage dividing circuit that resistance-divides the standard voltage by connecting, in series, resistors having the same temperature characteristics; and an instrumentation amplifier that generates the reference voltage according to the difference between the divided output voltages of the first and second resistance voltage dividing circuits.

Low-noise, low-power, low drift offset correction in operational and instrumentation amplifiers and amplifiers using the same are disclosed. The amplifiers disclosed use different combinations of chopping and auto-zero techniques. Also disclosed are amplifiers using on-off switches to affect the chopping and auto-zeroing, with unique circuits for driving the switches on the differential input to provide boot-strapped switch controls. Other features are disclosed.

The invention discloses a circuit for detecting dynamic weak capacitance of a micro electro mechanical system (MEMS) device, which is mainly applied to change detection of dynamic weak capacitance in a capacitive MEMS device. The circuit comprises a driving signal generation circuit, a capacitance to voltage (C/V) converting unit, a primary sampling and holding unit, a secondary sampling and holding unit and a signal processing unit. The driving signal generation circuit performs self-oscillation to generate a sine wave signal with fixed amplitude and frequency, and provides a detection pumping signal for the C/V converting unit; the C/V converting unit converts the weak capacitance variation into voltage, and a sine wave signal which can be processed by the subsequent stage of a samplingand holding circuit is output by an instrument amplifier; and the primary sampling and holding unit detects a positive peak point of the input sine wave, and when the positive peak point is detected,the output signal keeps the voltage of the positive peak point and half sine wave cycle is kept unchanged, the latter half cycle changes along with the input signal, and the output signal is used as a signal to be detected of the secondary sampling and holding unit.

The invention discloses a fully differential force balance mode MEMS acceleration sensor signal processing circuit comprising a fully differential switched capacitor circuit, a sampling and holding circuit, an instrument amplifier, a multiphase clock circuit and a reference source circuit. The fully differential switched capacitor circuit detects the MEMS change capacitance and outputs differential signals to be connected with the instrument amplifier through the sampling and holding circuit, and the differential signals are converted into single-end output signals through the instrument amplifier. According to the acceleration sensor signal processing circuit, high-precision and low-noise voltage output can be realized; and the designed acceleration sensor signal processing circuit works in a force balance second-order simulation closed-loop system and can convert the output voltage of the front-end detection circuit into electrostatic force to be fed back to the intermediate pole plate so that the mass block is maintained to vibrate near the balance position, and thus the circuit has high sensitivity.

This invention presents a method and apparatus for measuring the resistance across a fuel cell stack, a fuel cell array, or an individual fuel cell. The invention employs a fixed load circuit to switch a fixed resistance or to connect a fixed load current to the stack or array. When the load is turned on, the stack voltage is read, then the load is turned off and the stack voltage is read again to determine the voltage jump. A change in resistance is calculated that is related to cell hydration. In accordance with another aspect of the invention, the stack includes a programmable DC-DC switch under PWM microprocessor control. The DC-DC converter is used to switch the load on and off and the voltage jump is read using a sample and hold methodology with an optional instrumentation amplifier and a Kalman filter to determine accurate results for resistance with no additional hardware. The resistance measurements are used to identify and evaluate cell hydration.

The invention discloses an underwater data recorder system low in power consumption and belongs to the technical field of underwater sound communication. The data recorder system can collect underwater sound signals and store the signals into a storage module in the data recorder system, can be used in the deep sea environment conveniently and is low in power consumption. The data recorder system specifically comprises an underwater sound signal collecting module, a pre-amplifier, a filter, a pressure sensor, an instrument amplifier, a controller, the storage module and a power source. The underwater sound signal collecting module is used for collecting the underwater sound signals, the collected underwater sound signals are amplified and filtered, then the controller carries out A/D conversion on the underwater sound signals, and the underwater sound signals are written into the storage module through a set format. The pressure sensor is used for collecting pressure data of the working environment of a data recorder so as to obtain the actual depth of underwater working of the data recorder. The system reduces the power consumption of the data recorder by managing the work mode and the work procedure of the data recorder with the lower power consumption, and therefore the data recorder can work independently underwater for a long time.