KEITHLEY INSTRUMENTS, INC.
|KEITHLEY INSTRUMENTS, INC. Patent applications|
|Patent application number||Title||Published|
|20140015612||POWER ENVELOPE CONTROLLER AND METHOD - A power envelope controller configured for use with an amplification stage and method are disclosed. The power envelope controller includes voltage feedback input circuitry configured to receive a voltage feedback signal representing an internal voltage drop across the amplification stage and current feedback input circuitry configured to receive a current feedback signal representing an output current of the amplification stage. An analog multiplier is configured to generate an internal power dissipation signal representing the internal power dissipation of the amplification stage based on the voltage and current feedback signals. A comparator circuit is configured to compare the internal power dissipation signal to a power threshold and generate a power control error signal when the internal power dissipation of the amplification stage exceeds the threshold.||01-16-2014|
|20130285629||Dynamic Current Limit Apparatus and Method - A dynamic current limiter circuit is disclosed. The dynamic current limiter includes an input node an output node. The dynamic current limiter also includes a current control valve coupled between the input and output nodes, the current control valve being configured to limit current flow between the input and output nodes based on a control input. The dynamic current limiter also includes a current change detector coupled between the input and output nodes, the current change detector being configured to detect a change in current through the input and output nodes and generate a control signal configured to drive the control input. The current control valve is configured to limit current flow between the input and output nodes in response to the current control signal.||10-31-2013|
|20130265110||HIGH GAIN, HIGH VOLTAGE POWER AMPLIFIER - An opto-isolated amplifier and method are disclosed. The amplifier includes an input node configured to receive an input to be amplified. A pair of opto-isolators are coupled between an input node and an output node. The opto-isolators are configured to create gain between the input node and the output node. An amplification stage is coupled to the opto-isolators. The amplification stage includes an input coupled to the output node and an output configured to generate an amplified output. The opto-isolator outputs may be configured to generate a difference current. The input of the amplification stage may have a high impedance compared to an impedance at the output node, the difference current being directed at the high input impedance input of the amplification stage to generate a gained voltage.||10-10-2013|
|20130113511||DC-AC PROBE CARD TOPOLOGY - A DC-AC probe card for testing a DUT includes: a plurality of probe needles, each probe needle having a distal end for contacting said DUT; and a plurality of connection pathways operable to connect test instrumentation to the probe needles, wherein each connection pathway provides both a desired characteristic impedance for AC measurements and a guarded pathway for DC measurements between respective test instrument connections and probe needles.||05-09-2013|
|20090273338||ACTIVE AUTORANGING CURRENT SENSING CIRCUIT - A range-changing circuit for a measurement device having a desirable range includes an array of graduated impedances. And amplifier supplies an electrical voltage to at least one of the impedances of the array. A voltage sensing and limiting switch is provided in a feedback path of the amplifier. The switch limits said electrical voltage supplied to said at least one of the impedances in response to a sensed voltage that is sensed by the switch. An electrical voltage in the desirable range is developed across a different one of the impedances of the array based on an operation of the switch.||11-05-2009|
|20090201822||SWITCH MATRIX - A switch matrix for selectively connecting at least one of N signal inputs to at least one of M signal outputs, N and M being integers greater than two, includes a cluster of N input switches arranged about each of the M signal outputs resulting in at least M clusters of N input switches, each input switch having a switch input and a switch output, the switch outputs being connected to respective signal outputs, the clusters and the input switches in the clusters being arranged to permit adjacent switch inputs of adjacent clusters to be connected to form input switch nodes; and a steering switch for each of the signal inputs. The steering switch selectably connects a signal input to an input switch node, wherein the combination of the steering switches and the input switches are operable to connect a desired signal input to a desired signal output.||08-13-2009|
|20090195261||IMPEDANCE MEASURING INSTRUMENT - A measurement instrument for measuring the impedance of a device under test (DUT) includes a first source of either a voltage or a current and a second source of either a voltage or a current, wherein the first source is connectable in a first feedback relationship with the DUT and the second source is connectable in a second feedback relationship with both the DUT and the first source. The first and second sources are operated respectively as a current source responsive to the current through the DUT and a voltage source responsive to the voltage across the DUT or operated respectively as a voltage source responsive to the voltage across the DUT and a current source responsive to the current through the DUT. The second feedback relationship has a narrower bandwidth than the first feedback relationship. The resulting voltage across the DUT and the current through the DUT establish the measured impedance of the DUT.||08-06-2009|
|20090048800||TEST INSTRUMENT NETWORK - A test instrument network for testing a plurality of DUTs includes a plurality of communicating script processors, the script processors being adapted to execute computer code; and a plurality of measurement resources controllable by the script processors in response to executed computer code, the measurement resources being adapted to test the DUTs. Each script processor and measurement resource may be arbitrarily assigned by the controller to one of at least two groups, only one script processor being assigned to be a master script processor, any other script processor being a slave script processor and any group not including the master script processor being a remote group. The master script processor is exclusively authorized to initiate code execution on any script processor in a remote group. Any slave script processor is only able to initiate operation of measurement resources in it own group. When a particular script processor is executing computer code, the master script processor may not initiate execution of computer code on a member script processor in the group of the particular script processor and may not initiate operation of a member measurement resource in the group of the particular script processor.||02-19-2009|
|20080303535||MULTI-PIN CV MEASUREMENT - A method for measuring electrical parameters of a DUT having at least three terminals includes applying a first AC voltage to a first terminal; separately driving a second and a third terminal each to a virtual second AC voltage, each virtual voltage requiring a respective current; and measuring an electrical parameter of the DUT based on the first AC voltage and the second and third terminals each being at the virtual second AC voltage.||12-11-2008|
Patent applications by KEITHLEY INSTRUMENTS, INC.