National Instruments

About: National Instruments is a company organization based out in Dublin, Ireland. It is known for research contribution in the topics: Signal & Interface (computing). The organization has 1135 authors who have published 1719 publications receiving 35682 citations. The organization is also known as: NI & National Instruments Corporation.

Current mode track and hold circuit

Abstract: A current mode track and hold(T/H) circuit is provided having a high degree of accuracy. The current mode T/H circuit includes an input node, and output node, a voltage controlled current source, and a switched integretor circuit. The input node is configured to receive an input analog current signal and a feedback current provided by the voltage controlled current source. The output node is configured to receive an output analog current signal generated by the voltage controlled current source. The feedback current is equal to the output current, and both are proportional to a control voltage generated by the switched integrator circuit. The switched integrator circuit operates in either a tracking mode or a holding mode in accordance with a received binary T/H control signal. In the tracking mode, charge produced by a difference between the feedback current and the input analog current is integrated by the switched integrator circuit. Integration of charge causes a change in the control voltage generated by the switched integrator circuit. The change in control voltage, in turn, causes a change in feedback current until a steady rate is reached wherein the feedback current, and there by the output current, equals the input current. In the holding mode, the voltage controlled current source maintains the output at a constant value equal to the input current at a point in time when the switch circuit transitions from the tracking mode to the holding mode.

Mechanisms for the Correction of I/Q Impairments

Abstract: Various embodiments of communication devices and associated methods for reducing I/Q impairments in signals used by the communication devices are described. A transmitter device 206 may perform filtering (or matrix multiplication) on digital I and Q signals to pre-correct them before converting them into analog I and Q signals. The pre-correction may pre-compensate for I/Q impairments which have not been introduced yet, but which will subsequently be introduced during digital to analog conversion, I/Q modulation, or other processing that occurs to produce a transmission signal from the original digital I and Q signals. A receiver device may receive a transmission signal, produce digital I and Q signals from it, and perform filtering on the digital I and Q signals to correct I/Q impairments at a plurality of frequency offsets.

Network-Based System for Automatically Generating a Graphical Program Based on User Supplied Measurement Task Requirements

Abstract: A system and method for online configuration of a measurement system. The user may access a server over a network and specify a desired task, e.g., a measurement task, and receive programs and/or configuration information which are usable to configure the user's measurement system hardware (and/or software) to perform the desired task. Additionally, if the user does not have the hardware required to perform the task, the required hardware may be sent to the user, along with programs and/or configuration information. The hardware may be reconfigurable hardware, such as an FPGA or a processor/memory based device. In one embodiment, the required hardware may be pre-configured to perform the task before being sent to the user. In another embodiment, the system and method may provide a graphical program in response to receiving the user's task specification, where the graphical program may be usable by the measurement system to perform the task.

Protection and voltage monitoring circuit

Abstract: A protection and voltage monitoring circuit that may provide the functionality of a diode without the typical large voltage drop and power dissipation. The protection and voltage monitoring circuit may include a first MOSFET, a second MOSFET, a first resistor, an input terminal, an output terminal, a diode, a BJT current source, and a voltage monitoring circuit. The BJT current source may limit a gate-to-source voltage of the two MOSFETs to a predetermined voltage that is less than a maximum allowed voltage by controlling a current flow through the first resistor to prevent damage to the MOSFETs. The voltage monitoring circuit may determine whether an external voltage is within an allowable range of voltages. If the external voltage is outside the predetermined voltage range, the voltage monitoring circuit turns off the BJT current source to block the external voltage from the output terminal of the protection and voltage monitoring circuit.

Programmable Controller with Multiple Processors Using Scanning and Data Acquisition Architectures

Abstract: Operating a programmable controller with a plurality of processors. The programmable controller may utilize a first subset of the plurality of processors for a scanning architecture. The first subset of the plurality of processors may be further subdivided for execution of periodic programs or asynchronous programs. The programmable controller may utilize a second subset of the plurality of processors for a data acquisition architecture. Execution of the different architectures may occur independently and may not introduce significant jitter (e.g., for the scanning architecture) or data loss/response time lag (e.g., for the data acquisition architecture). However, the programmable controller may operate according to any combination of the divisions and/or architectures described herein.