Full differential data qualification circuit for sensing a logic state
First Claim
1. A data qualification circuit for translating an applied differential input voltage to an output signal having first or second predetermined level logic states, comprising:
- a comparator having first and second inputs and at least one output at which the output signal is provided;
a first threshold circuit responsive to the output signal being at the second logic level state for providing a first threshold level signal across said first and second inputs of said comparator, said first threshold circuit being programmable to adjust a magnitude of said first threshold level signal;
a second threshold circuit responsive to the output signal being at the first logic level state for providing a second threshold level signal across said first and second inputs of said comparator, said second threshold circuit being programmable to adjust a magnitude of said second threshold level signal; and
an input circuit responsive to the differential input voltage for providing an output signal across said first and second inputs of said comparator, said first and second threshold level signals being summed with said output signal of said input circuit as said first and second threshold circuits are rendered operative in response to said output signal from said comparator.
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Accused Products
Abstract
A data qualification circuit (11) comprises a comparator (28), a first threshold circuit (33), and a second threshold circuit (41). A differential input signal is applied to the data qualification circuit (11). A first threshold circuit (33) is enabled by a zero logic state at the output of comparator (28). The first threshold circuit (33) sets a one logic state threshold voltage which the differential input signal must overcome for the comparator (28) to generate a one logic state. A second threshold circuit (41) is enabled by a zero logic state at the output of comparator (28). The second threshold circuit (41) sets a zero logic state threshold voltage which the differential input signal must overcome for the comparator (28) to generate a zero logic state.
11 Citations
20 Claims
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1. A data qualification circuit for translating an applied differential input voltage to an output signal having first or second predetermined level logic states, comprising:
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a comparator having first and second inputs and at least one output at which the output signal is provided; a first threshold circuit responsive to the output signal being at the second logic level state for providing a first threshold level signal across said first and second inputs of said comparator, said first threshold circuit being programmable to adjust a magnitude of said first threshold level signal; a second threshold circuit responsive to the output signal being at the first logic level state for providing a second threshold level signal across said first and second inputs of said comparator, said second threshold circuit being programmable to adjust a magnitude of said second threshold level signal; and an input circuit responsive to the differential input voltage for providing an output signal across said first and second inputs of said comparator, said first and second threshold level signals being summed with said output signal of said input circuit as said first and second threshold circuits are rendered operative in response to said output signal from said comparator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A circuit for translating an applied differential input voltage to an output signal having first or second predetermined level logic states, comprising:
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a comparator having first and second inputs and at least one output at which the output signal is provided; a load circuit for summing signals applied thereto, said load circuit having a first terminal coupled to said first input of said comparator and a second terminal coupled to said second input of said comparator; a first threshold circuit responsive to the output signal being at the second logic level state for providing a first threshold level signal across said first and second terminals of said load circuit, said first threshold circuit being programmable to adjust a magnitude of said first threshold level signal; a second threshold circuit responsive to the output signal being at the first logic level state for providing a second threshold level signal across said first and second terminals of said load circuit, said second threshold circuit being programmable to adjust a magnitude of said second threshold level signal; and an input circuit responsive to the differential input voltage for providing an output signal across said first and second terminals of said load circuit, said first and second threshold level signals being summed with said output signal of said input circuit as said first and second threshold circuits are rendered operative in response to said output signal from said comparator. - View Dependent Claims (11, 12)
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13. A circuit for translating an applied differential input voltage to an output signal having first or second predetermined level logic states, comprising:
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a comparator having first and second inputs and at least one output at which the output signal is provided; a load circuit for summing signals applied thereto, said load circuit having a first terminal coupled to said first input of said comparator and a second terminal coupled to said second input of said comparator, said load circuit comprises a first resistor including a first terminal coupled to a terminal of a power supply and a second terminal corresponding to said first terminal of said load circuit and a second resistor including a first terminal coupled to said terminal of said power supply and a second terminal corresponding to said second terminal of said load circuit; a first threshold circuit responsive to the output signal being at the second logic level state for providing a first threshold level signal across said first and second terminals of said load circuit, said first threshold circuit comprises a switch circuit responsive to the output signal being at the second logic level, said switch circuit including a first input, a second input, a first output coupled to said first terminal of said load circuit, and a second output coupled to said second terminal of said load circuit; a voltage to current circuit responsive to an applied reference voltage and providing said differential current signal to said load circuit when coupled thereto by said switch circuit, said voltage to current circuit comprising; a first transistor including a control terminal coupled to a first input of said first threshold circuit, a first terminal coupled to said first input of said switch circuit, and a second terminal; a second transistor including a control terminal coupled to a second input of said first threshold circuit, a first terminal coupled to said second input of said switch circuit, and a second terminal, said first and second inputs of said first threshold circuit receiving said applied reference voltage; a resistor coupled between said second terminal of said first transistor and said second terminal of said second transistor; a first current source for biasing said first transistor including a terminal coupled to said second terminal of said first transistor; a second current source for biasing said second transistor including a terminal coupled to said second terminal of said second transistor; a second threshold circuit responsive to the output signal being at the first logic level state for providing a second threshold level signal across said first and second terminals of said load circuit; and an input circuit responsive to the differential input voltage for providing an output signal across said first and second terminals of said load circuit, said first and second threshold level signals being summed with said output signal of said input circuit as said first and second threshold circuits are rendered operative in response to said output signal from said comparator; wherein said input circuit, first threshold circuit, and second threshold circuit each provide a differential current signal corresponding respectively to said output signal of said input circuit, said first threshold level signal, and said second threshold level signal. - View Dependent Claims (14, 15, 16)
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17. A full differential data qualification circuit for translating an applied differential input voltage to an output signal having first or second predetermined logic level states, the full differential data qualification circuit comprising:
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a comparator including a first input, a second input, and at least one output at which the output signal is provided; a first threshold circuit for providing a first threshold level signal across said first and second inputs of said comparator, said first threshold circuit including a first input, a second input, a control input coupled to said output of said comparator, a first output coupled to said first input of said comparator, and a second output coupled to said second input of said comparator, said first and second inputs of said first threshold circuit being responsive to an applied first reference voltage, said first and second outputs providing said first threshold level signal when rendered operative by the output signal being in the second predetermined logic level state, said first threshold circuit being programmable to adjust a magnitude of said first threshold level signal; a second threshold circuit for providing a second threshold level signal across said first and second inputs of said comparator, said second threshold circuit including a first input, a second input, a control input coupled to said output of said comparator, a first output coupled to said second input of said comparator, and a second output coupled to said first input of said comparator, said first and second inputs of said second threshold circuit being responsive to an applied second reference voltage,. said first and second outputs providing said second threshold level signal when rendered operative by the output signal being in the first predetermined logic level state, said second threshold circuit being programmable to adjust a magnitude of said second threshold level signal; and an input circuit for providing an output signal across said first and second inputs of said comparator, said input circuit including a first input, a second input, a first output coupled to said first input of said comparator, and a second input coupled to said second input of said comparator, said first and second inputs receiving the applied differential input voltage. - View Dependent Claims (18, 19, 20)
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Specification