IMPEDANCE CONVERTER CIRCUIT
First Claim
1. An impedance converter module comprising:
- a phase reversal circuit to receive a 2-wire excitation signal at first and second terminals, and to provide a polarized excitation signal with a predetermined polarity based on the 2-wire excitation signal;
a series current path comprising a sense resistor connected in series with a variable impedance source, the polarized excitation signal being applied across the series current path;
an output-voltage-sense circuit to provide an output-voltage-sense signal based on a voltage across the series current path;
a current mirror to provide a drive signal to a ratiometric device based on current flowing through the series current path;
differential amplifiers to receive a ratiometric response signal from the ratiometric device, and to output measurement signals based on the ratiometric signal; and
a summing node to combine the measurement signals to provide a single-ended ratiometric signal;
wherein the variable impedance source is controlled to provide a two-wire response signal at the 2-wire terminals based on the single-ended ratiometric signal and the output-voltage-sense signal.
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Accused Products
Abstract
An impedance converter module has a phase reversal circuit to receive a 2-wire excitation signal at first and second terminals, and to provide a polarized excitation signal with a predetermined polarity based on the 2-wire excitation signal. A series current path has a sense resistor connected in series with a variable impedance source. The polarized excitation signal is applied across the series current path. An output-voltage-sense circuit provides an output-voltage-sense signal based on a voltage across the series current path. A current mirror provides a drive signal to a ratiometric device based on current flowing through the series current path. Differential amplifiers receive a ratiometric response signal from the ratiometric device, and output measurement signals based on the ratiometric signal. A summing node combines the measurement signals to provide a single-ended ratiometric signal. The variable impedance source is controlled to provide a two-wire response signal at the 2-wire terminals based on the single-ended ratiometric signal and the output-voltage-sense signal.
27 Citations
20 Claims
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1. An impedance converter module comprising:
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a phase reversal circuit to receive a 2-wire excitation signal at first and second terminals, and to provide a polarized excitation signal with a predetermined polarity based on the 2-wire excitation signal;
a series current path comprising a sense resistor connected in series with a variable impedance source, the polarized excitation signal being applied across the series current path;
an output-voltage-sense circuit to provide an output-voltage-sense signal based on a voltage across the series current path;
a current mirror to provide a drive signal to a ratiometric device based on current flowing through the series current path;
differential amplifiers to receive a ratiometric response signal from the ratiometric device, and to output measurement signals based on the ratiometric signal; and
a summing node to combine the measurement signals to provide a single-ended ratiometric signal;
wherein the variable impedance source is controlled to provide a two-wire response signal at the 2-wire terminals based on the single-ended ratiometric signal and the output-voltage-sense signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A catheter comprising:
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a thermistor to sense a temperature;
a pad resistor coupled to the thermistor, wherein the output of the pad resistor and the thermistor provide a ratiometric response signal; and
an impedance converter circuit comprising;
a phase reversal circuit to receive a 2-wire excitation signal at first and second terminals, and to provide a polarized excitation signal with a predetermined polarity based on the 2-wire excitation signal;
a series current path comprising a sense resistor connected in series with a variable impedance source, the polarized excitation signal being applied across the series current path;
an output-voltage-sense circuit to provide an output-voltage-sense signal based on a voltage across the series current path;
a current mirror to provide a drive signal to the pad resistor and thermistor based on current flowing through the series current path;
differential amplifiers to receive the ratiometric response signal, and to output measurement signals based on the ratiometric signal; and
a summing node to combine the measurement signals to provide a single-ended ratiometric signal;
wherein the variable impedance source is controlled to provide a two-wire response signal at the 2-wire terminals based on the single-ended ratiometric signal and the output-voltage-sense signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification