Common mode rejection coupler

In a circuit having a common mode voltage between the input and 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;
• wave shaping means for converting said first and second signals to first and second square waves signals having first and second states;
• means for inverting one of said first and second square wave signals, said first and second square wave signals being thereby in-phase with one another;
• and
• discriminating means receiving said in-phase first and second square wave signals for generating an output signal having first or second states, said disciminating means changing the state of said output signal only when both of said in-phase signals change state, spurious changes in the state of only one of said first and second signals being ineffective to change the state of said output signal.

In a circuit having a common mode voltage between the input and 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, 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;
• means for inverting one of said first and second signals, said first and second signals being thereby in-phase with one another;
• and
• disciminating means receiving said in-phase first and second signals for generating an output signal having first or second states, said discriminating means changing the state of said output signal only when both of said in-phase signals complement states wherein changes in one or the other of said first and second signals are ineffective to change said output signal state.

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:

• 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 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 having a state opposite that of said first signal;
• means for inverting one of said first and second signals, said first and second signals thereby having the same state;
• and
• logic means receiving said first and second signals for generating an output having a first state when said first and second signals have a first state and for generating an output having a second state when said first and second signals have a second state, said logic means being ineffective to change output states when one of said first and second signals has a state opposite the other.