Common mode rejection coupler
First Claim
1. In a circut having a comon mode voltage between the input and the output thereof, a common mode rejection coupler comprising:
- a first circuit means for receiving an input signal and for generating a first signal in response thereto, said first circuit means normally isolating said first signal with respect to said common mode voltage;
a second circuit means for receiving the complement of said input signal and for generating a second signal in response thereto, said second circuit means normally isolating said second signal with respect to said common mode voltage, said second signal being the complement of said first signal;
a comparator for receiving said first and second signals and for generating at least one output signal, said comparator changing the output signal state when said first and second signals complement states; and
means connected to the output of said comparator for limiting the magnitude of transient changes in one of said first and second signals to less than the magnitude of the non-transient difference between said first and second signals, said limiting means preventing said comparator from changing state when a common mode transient voltage change occurs in one of said first and second signals.
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Accused Products
Abstract
A common mode rejection coupler in a power switching system having a variable common mode voltage includes a first optical isolator circuit for receiving an input signal and generating in response thereto a first signal which is normally isolated with respect to the common mode voltage. A second optical isolator circuit receives the complement of the input signal and generates a second signal which is also normally isolated with respect to the common mode voltage. The first and second signals are the complement of one another. A comparator receives the first and second signals and generates an output signal which changes state only when the first and second signals complement states. Feedback control circuitry for the comparator is provided for limiting transient changes in one of the first and second signals to prevent the comparator from changing output states when a transient change occurs in one of the first and second signals resulting from a change in the common mode voltage.
24 Citations
9 Claims
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1. In a circut having a comon mode voltage between the input and the output thereof, a common mode rejection coupler comprising:
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a first circuit means for receiving an input signal and for generating a first signal in response thereto, said first circuit means normally isolating said first signal with respect to said common mode voltage; a second circuit means for receiving the complement of said input signal and for generating a second signal in response thereto, said second circuit means normally isolating said second signal with respect to said common mode voltage, said second signal being the complement of said first signal; a comparator for receiving said first and second signals and for generating at least one output signal, said comparator changing the output signal state when said first and second signals complement states; and means connected to the output of said comparator for limiting the magnitude of transient changes in one of said first and second signals to less than the magnitude of the non-transient difference between said first and second signals, said limiting means preventing said comparator from changing state when a common mode transient voltage change occurs in one of said first and second signals.
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2. In a circuit for rejecting common mode voltage coupling between the input and output thereof, a common mode rejection coupler comprising:
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a first circuit means for receiving an input signal and for generating a first signal in response thereto, said first circuit means normally isolating said first signal with respect to said common mode voltage; a second circuit means for receiving the complement of said input signal and for generating a second signal in response thereto, said second circuit means normally isolating said second signal with respect to said common mode voltage, said second signal being the complement of said first signal, said first and second circuit means generating transient changes in one or the other of said first and second signals when said common mode voltage changes; a comparator for receiving said first and second signals and for generating at least one output signal, said comparator changing the output signal state when said first and second signals complement states; and means connected to the output of said comparator for limiting the magnitude of transient changes in one of said first and second signals to less than the magnitude of the non-transient difference between said first and second signals, said limiting means preventing said comparator from changing state when a common mode transient voltage change occurs in one of said first and second signals.
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3. In a power switching system having a low level input logic control circuit and a high level output power switch control circuit wherein a variable common mode voltage exists between said input and output circuits, a common mode rejection coupler comprising:
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a first circuit means for receiving an input signal and for generating a first signal in response thereto, said first circuit means normally isolating said first signal with respect to said common mode voltage; a second circuit means for receiving the complement of said input signal and for generating a second signal in response thereto, said second circuit means normally isolating said second signal with respect to said common mode voltage, said second signal being the complement of said first signal, said first and second circuit means generating transient changes in one or the other of said first and second signals when said common mode voltage changes; a comparator for receiving said first and second signals and for generating at least one output signal, said comparator changing the output signal state when said first and second signals complement states; and means connected to the output of said comparator for limiting the magnitude of transient changes in one of said first and second signals to less than the magnitude of the non-transient difference between said first and second signals, said limiting means preventing said comparator from changing state when a common mode transient voltage change occurs in one of said first and second signals. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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Specification