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US 8,106,669 B2Granted
High current precision resistance measurement system
AssigneeGuildline Instruments Limited
InventorsAndre C Perras, Mark Evans
Life of this patent
Estimating the term…
Abstract
A resistance testing apparatus makes use of a modular design for cascaded, parallel, bipolar current sources to obviate the need for electromechanical or pneumatic switching systems.
Claims20
A resistance measurement system for generating a bi-polar current comprising:
- a bridge having
- a controller,
- a digital to analog converter for generating a first signal having a defined bi-polar current,
- a first current tracking amplifier for generating a second signal having a defined bi-polar current, and for transmitting the generated second signal to a reference resistor,
- a first comparator for receiving the output of the first current tracking amplifier en route to the reference resistor and for controlling a switch to place the bridge into a first state and a second state, the first state connecting a secondary input of the bridge to ground and the second state connecting the output of the digital to analog converter to a test resistance;
- an extender having
- a bi-polar amplifier for receiving the output of the digital to analog converter in the bridge, for amplifying the received converter output, and for transmitting the amplified current signal as an output, and
- a second comparator for receiving the output of the bipolar amplifier, for controlling a second current tracking amplifier to generate and transmit a signal having a defined bi-polar current to the secondary input of the bridge, and for receiving the output of the second current tracking amplifier en route to the secondary input of the bridge;
- and
- a high current extender having
- a high current bi-polar amplifier for receiving as an input, the output of the digital to analog converter, for amplifying the received input, and for transmitting the amplified signal to the test resistance;
- and
- a high current comparator for receiving the outputs of the high current bi-polar amplifier and the bi-polar amplifier for controlling a servo current tracking amplifier to generate and transmit a signal having defined bi-polar current to the input of the bi-polar amplifier in the extender.
10 more elements
A method comprising:
- determining an unknown resistance in dependence upon at least a ratio of a test current and a reference current, each current established through setting a state of a resistance measurement system into each of a first state and a second state, the resistance measurement system for generating a bi-polar current and comprising:
- a bridge having
- a controller,
- a digital to analog converter for generating a first signal having a defined bi-polar current,
- a first current tracking amplifier for generating a second signal having a defined bi-polar current, and for transmitting the generated second signal to a reference resistor,
- a first comparator for receiving the output of the first current tracking amplifier en route to the reference resistor and for controlling a switch to place the resistance measurement system into the first state and the second state, the first state connecting a secondary input of the bridge to ground and the second state connecting the output of the digital to analog converter to a test resistance;
- an extender having
- a bi-polar amplifier for receiving the output of the digital to analog converter in the bridge, for amplifying the received converter output, and for transmitting the amplified current signal as an output, and
- a second comparator for receiving the output of the bipolar amplifier, for controlling a second current tracking amplifier to generate and transmit a signal having a defined bi-polar current to the secondary input of the bridge, and for receiving the output of the second current tracking amplifier en route to the secondary input of the bridge;
- and
- a high current extender having
- a high current bi-polar amplifier for receiving as an input, the output of the digital to analog converter, for amplifying the received input, and for transmitting the amplified signal to the test resistance;
- and
- a high current comparator for receiving the outputs of the high current bi-polar amplifier and the bi-polar amplifier for controlling a servo current tracking amplifier to generate and transmit a signal having defined bi-polar current to the input of the bi-polar amplifier in the extender.
11 more elements
Dependencies are inferred from the claim text.