Circuit arrangement for evaluating the output signal of an active sensor
First Claim
1. A circuit for evaluating an output signal of an active sensor which is configured as a binary current signal having a square-wave output signal with two different current levels, comprising:
- means for producing a signal current proportional to the sensor output signal by way of a current mirror circuit,the signal current induced by a first circuit branch of said current mirror circuit is drawn from a voltage source by way of an ohmic resistance, whereby a binary voltage signal corresponding to the sensor output signal is generated,comparator means having a first input coupled to said binary voltage signal, wherein said comparator means includes hysteresis characteristics which are implemented by comparing the binary voltage signal with a reference signal, wherein said reference signal is composed of a serial connection of a reference voltage and a hysteresis voltage, wherein the change-over threshold of the comparator means is responsive to the reference value signal, whereinthe reference voltage is varied as a function of the sensor output signal, and wherein the reference voltage is produced by way of a capacitor which is connected to a second input of said comparator means.
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Accused Products
Abstract
To evaluate the output signal of an active sensor which is configured as a binary current signal, a circuit arrangement is disclosed by which a proportional current is produced from the sensor current by way of a current mirror circuit. The current produced by a current mirroring operation is drawn from a stabilized voltage source by way of an ohmic resistance, and a binary voltage signal corresponding to the sensor output signal is generated thereby. The voltage signal is sent to a flipflop which compares the voltage signal with a reference value that is composed of a reference voltage and a hysteresis voltage. The change-over threshold of the flipflop is varied or adapted as a function of the actual sensor current, leakage currents, etc.
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Citations
7 Claims
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1. A circuit for evaluating an output signal of an active sensor which is configured as a binary current signal having a square-wave output signal with two different current levels, comprising:
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means for producing a signal current proportional to the sensor output signal by way of a current mirror circuit, the signal current induced by a first circuit branch of said current mirror circuit is drawn from a voltage source by way of an ohmic resistance, whereby a binary voltage signal corresponding to the sensor output signal is generated, comparator means having a first input coupled to said binary voltage signal, wherein said comparator means includes hysteresis characteristics which are implemented by comparing the binary voltage signal with a reference signal, wherein said reference signal is composed of a serial connection of a reference voltage and a hysteresis voltage, wherein the change-over threshold of the comparator means is responsive to the reference value signal, wherein the reference voltage is varied as a function of the sensor output signal, and wherein the reference voltage is produced by way of a capacitor which is connected to a second input of said comparator means. - View Dependent Claims (2, 3, 4)
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5. A circuit for evaluating an output signal of an active sensor which is configured as a binary current signal having a square-wave output signal with two different current levels, comprising:
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means for producing a signal current proportional to the sensor output signal by way of a current mirror circuit, the signal current induced by a first circuit branch of said current mirror circuit is drawn from a voltage source by way of an ohmic resistance, whereby a binary voltage signal corresponding to the sensor output signal is generated, comparator means having a first input coupled to said binary voltage signal, wherein said comparator means includes hysteresis characteristics which are implemented by comparing the binary voltage signal with a reference signal coupled to a second input of said comparator mean, wherein said reference signal is composed of a serial connection of a reference voltage and a hysteresis voltage, wherein the change-over threshold of the comparator means is responsive to the reference signal, wherein the reference voltage is varied as a function of the sensor output signal wherein the reference voltage is produced by way of a capacitor which is connected to a second circuit branch of the current mirror circuit by way of an ohmic resistance. - View Dependent Claims (6, 7)
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Specification