Low current high precision CMOS schmitt trigger circuit
First Claim
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1. A Schmitt Trigger circuit comprising:
- a differential comparator having a first input for receiving an input signal, a second input for receiving a comparison signal to be compared to the input signal, an output switchable from a first output state to a second output state, and power supply terminals for the application of current from a power supply to the comparator;
feedback means, coupled to the second input, for providing one of a predetermined first and second voltages as the comparison signal in accordance with the output state of the comparator, said feedback means including power supply terminals for the application of current from the power supply to the feedback means; and
switch means, coupled to at least one of the power supply terminals of the comparator and feedback means and controlled by the input signal, for controlling the application of current from the power supply to at least one of the comparator and feedback means.
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Abstract
A CMOS Schmitt Trigger circuit includes a differential structure for comparing an input signal with a feedback signal and a feedback circuit for providing the feedback signal with one of two voltage levels. A CMOS switch pair is connected to one or both of the differential structure and feedback circuit to provide power to the circuit only when necessary so as to minimize power consumption.
37 Citations
24 Claims
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1. A Schmitt Trigger circuit comprising:
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a differential comparator having a first input for receiving an input signal, a second input for receiving a comparison signal to be compared to the input signal, an output switchable from a first output state to a second output state, and power supply terminals for the application of current from a power supply to the comparator; feedback means, coupled to the second input, for providing one of a predetermined first and second voltages as the comparison signal in accordance with the output state of the comparator, said feedback means including power supply terminals for the application of current from the power supply to the feedback means; and switch means, coupled to at least one of the power supply terminals of the comparator and feedback means and controlled by the input signal, for controlling the application of current from the power supply to at least one of the comparator and feedback means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A Schmitt Trigger circuit comprising:
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a differential section including first and second MOS transistors having their sources interconnected and an output at the drain of one of the transistors, an input terminal connected to the gate of the first transistor for receiving an input signal, and a feedback terminal connected to the gate of the second transistor for receiving a feedback signal, wherein the output will be a first level when the input signal is greater than the feedback signal and a second level when the input signal is less than the feedback signal; a feedback section, coupled to the feedback terminal and controlled by the output of the differential section, for providing one of a predetermined first and second signals as the feedback signal; a power supply terminal for supplying power to at least one of the differential section and feedback section; and CMOS switch means, connected to the power supply terminal and controlled by the input signal, for controlling the application of power to at least one of the differential section and the feedback section. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A CMOS Schmitt Trigger circuit comprising:
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power supply means for supplying power to the circuit, said power supply means having first and second power supply terminals; a differential comparator section, coupled to receive power from the first power supply terminal, including first and second MOS transistors having their sources interconnected and an output at the drain of one of the transistors, an input terminal connected to the gate of the first transistor for receiving an input signal, and a feedback terminal connected to the gate of the second transistor for receiving a feedback signal, wherein the output will be a first level when the input signal is greater than the feedback signal and a second level when the input signal is less than the feedback signal; a feedback section, coupled to receive power from the second power supply terminal and to be controlled by the output of the differential section, for providing to the feedback terminal one of a predetermined first and second feedback voltages as the feedback signal; and CMOS switch means, including at least a third MOS transistor connected to the first power supply terminal and controlled by the input signal and a fourth MOS transistor connected to the second power supply terminal and controlled by the input signal, for controlling the application of power to the differential section and the feedback section, said third and fourth transistors being rendered simultaneously conductive for a range of input signal values that includes the first and second feedback volages.
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Specification