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US 5,666,076 AGranted
Negative input voltage comparator
AssigneeCherry Semiconductor Corporation
InventorsRobert H. Fugere, James Alvernaz
Life of this patent
Estimating the term…
Abstract
A negative input voltage comparator that compares a negative input voltage signal against a positive voltage signal in a circuit, such as an integrated circuit. The negative input voltage signal is effectively isolated from the circuit by means of a series resistor in the base-emitter circuit of a transistor which is connected in the output leg of a current comparator.
Claims14
A negative input voltage comparator comprising:
- a supply means for receiving a power supply voltage;
- a current comparator connected to said supply means and having a first leg and a second leg;
- means for establishing an input current in the first leg of said current comparator using a positive voltage;
- a first resistor connected to an end of the second leg of said current comparator;
- an input port coupled to said first resistor opposite from the second leg of said current comparator to receive said negative input voltage;
- and
- an output node located on the second leg of said current comparator such that output current flows out from said output unless an amount of current through the first resistor is at least as large as the input current multiplied by a predetermined factor.
4 more elements
A negative input voltage comparator comprising:
- a supply means for receiving a supply voltage;
- a current mirror, coupled to said supply means, having an input current and an output current;
- a means, including a first input node, for establishing the input current in said current mirror;
- a transistor having a collector for receiving said output current of said current mirror, having a base connected to ground and having an emitter;
- an output node at the collector of said transistor;
- and
- a resistor coupled between the emitter of said transistor and a second input node of said comparator,
- wherein a negative voltage applied to said second input node is compared to a positive voltage applied to said first input node to selectively sink the output current of said current mirror to ground through said transistor.
5 more elements
A negative input voltage comparator comprising:
- a supply means for receiving a supply voltage;
- first and second input nodes;
- a current mirror coupled to said supply means and having an input current and an output current;
- a first transistor having a base connected to said first input node and a collector connected to said current mirror for conducting the input current of said current mirror;
- a first resistor coupled between the emitter of said first transistor and ground;
- a second transistor having a collector for receiving said output current of said current mirror, having a base connected to ground and having an emitter;
- a second resistor coupled between the emitter of said second transistor and said second input node;
- and
- a transistor switch having a base connected to the collector of said second transistor, a grounded emitter, and a collector that provides the switched output, wherein the switched output goes to a high voltage state when a negative voltage applied to said second input node has an absolute value greater than a positive voltage applied to the first input node multiplied by a predetermined factor.
6 more elements
Dependencies are inferred from the claim text.