Comparator with hysteresis
First Claim
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1. A comparator, comprising:
- a differential amplifier having a first input terminal, a second input terminal, and an output node, said differential amplifier being connected between a supply voltage and a reference potential;
a first resistor connected between said first input terminal and an input signal;
a second resistor connected between said second input terminal and a reference voltage;
a current mirror circuit connected between opposite ends of said second resistor and said reference potential;
an output voltage terminal;
an output amplifier coupled between said output node of said differential amplifier and said output voltage terminal;
a switch coupled between said current mirror circuit and said reference potential, said switch being responsive to the voltage at said output node for controlling the current value of said current mirror circuit, and thereby controlling the voltage at a node between said second resistor and said second input terminal of said differential amplifier.
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Abstract
A comparator with hysteresis in which a reference voltage of the comparator is easily adjustable. A resistor for dropping the reference voltage and a current source are coupled to a reference voltage terminal, and function to adjust the reference voltage in response to the level of an output voltage. Thus, the hysteresis voltage of the comparator can be easily adjusted by varying the current flowing through the resistor.
35 Citations
19 Claims
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1. A comparator, comprising:
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a differential amplifier having a first input terminal, a second input terminal, and an output node, said differential amplifier being connected between a supply voltage and a reference potential; a first resistor connected between said first input terminal and an input signal; a second resistor connected between said second input terminal and a reference voltage; a current mirror circuit connected between opposite ends of said second resistor and said reference potential; an output voltage terminal; an output amplifier coupled between said output node of said differential amplifier and said output voltage terminal; a switch coupled between said current mirror circuit and said reference potential, said switch being responsive to the voltage at said output node for controlling the current value of said current mirror circuit, and thereby controlling the voltage at a node between said second resistor and said second input terminal of said differential amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification