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US 6,441,650 B2Granted
Offset comparator and method for forming same
AssigneeADMtek Incorporated
InventorVaishali Nikhade
Life of this patent
Estimating the term…
Abstract
The comparator includes a differential stage having a first input and a second input, an output stage in which the output is zero when the two inputs have therebetween a specific voltage difference, and a biasing stage providing a first biasing voltage and a second biasing voltage for respectively creating a second input voltage and a first input voltage respectively in the second and first inputs such that the two input voltages have therebetween the specific voltage difference. A method for forming the same includes steps of a) providing the differential stage, b) providing the output stage and c) providing the biasing stage which has a characteristic dependent on a manufacturing parameter such that the specific voltage difference is independent of the manufacturing parameter.
Claims26
An offset comparator comprising:
- a differential stage having a first input and a second input;
- an output stage electrically connected to said differential stage in order that an output of said comparator is zero when said two inputs have therebetween a specific voltage difference;
- and
- a biasing stage electrically connected to said differential stage comprising:
- a first source follower for providing a first biasing voltage for creating a second input voltage to said second input;
- a second source follower for providing a second biasing voltage for creating a first input voltage to said first input in order that said two input voltages have therebetween said specific voltage difference;
- a first diode connected transistor electrically connected to said first source follower for providing thereto a first biasing current;
- and
- a second diode connected transistor electrically connected to said second source follower for providing thereto a second biasing current.
6 more elements
An offset comparator comprising:
- a differential stage having a first input and a second input;
- an output stage electrically connected to said differential stage in order that an output of said comparator is zero when said two inputs have therebetween a specific voltage difference;
- and
- a biasing stage electrically connected to said differential stage comprising:
- a first voltage provider for providing a second input voltage to said second input;
- a second voltage provider for providing a first input voltage to said first input in order that said two input voltages have therebetween said specific voltage difference;
- and
- a diode connected transistor electrically connected to said second voltage provider for providing thereto a relatively constant biasing current.
5 more elements
An offset comparator comprising:
- a differential stage having a first input and a second input;
- an output stage electrically connected to said differential stage in order that an output of said comparator is zero when said two inputs have therebetween a specific voltage difference;
- a biasing stage electrically connected to said differential stage, and providing a first biasing voltage for creating a second input voltage in said second input and providing a second biasing voltage for creating a first input voltage in said first input in order that said two input voltages have therebetween said specific voltage difference;
- and
- a bias-compensating circuit electrically connected to said biasing stage, which provides a bias current independent from said output of said comparator for compensating said second biasing voltage so as to provide a fixed trip voltage for said comparator, wherein said bias-compensating circuit includes:
- a fixed biasing current circuit for providing a fixed biasing current;
- and
- a variable current circuit electrically connected to said fixed biasing current circuit for providing a manufacturing parameter-dependent current.
5 more elements
An offset comparator comprising:
- a differential stage having a first input and a second input;
- an output stage electrically connected to said differential stage in order that an output of said comparator is zero when said two inputs have therebetween a specific voltage difference;
- a resistorless biasing stage electrically connected to said differential stage, providing a first biasing voltage for creating a second input voltage in said second input and providing a second biasing voltage for creating a first input voltage in said first input in order that said two input voltages have therebetween said specific voltage difference;
- and
- a bias-compensating circuit electrically connected to said biasing stage, which provides a bias current independent from said output of said comparator for compensating said second biasing voltage so as to provide a fixed trip voltage for said comparator, wherein said bias-compensating circuit includes:
- a fixed biasing current circuit for providing a fixed biasing current;
- and
- a variable current circuit electrically connected to said fixed biasing current circuit for providing a manufacturing parameter-dependent current.
5 more elements
An offset comparator comprising:
- a differential stage having a first input and a second input;
- an output stage electrically connected to said differential stage in order that an output of said comparator is zero when two inputs have therebetween a specific voltage difference;
- a first voltage provider electrically connected to said second input for providing therewith a second input voltage;
- a second voltage provider electrically connected to said first input for providing therewith a first input voltage;
- a biasing circuit electrically connected to said first and second voltage providers for providing a first biasing voltage to said second voltage provider and a second biasing voltage to said first voltage provider in order that said two input voltages have therebetween said specific voltage difference;
- and
- a bias-compensating circuit electrically connected to said second voltage provider, which provides a bias current independent from said output of said comparator for compensating said second biasing voltage so as to provide a fixed trip voltage for said comparator, wherein said bias-compensating circuit includes:
- a fixed biasing current circuit for providing a fixed biasing current;
- and
- a variable current circuit electrically connected to said fixed biasing current circuit for providing a manufacturing parameter-dependent current.
7 more elements
A method for forming an offset comparator comprising the steps of:
- a) providing a differential stage having a first input and a second input;
- b) providing an output stage electrically connected to said differential stage in order that an output of said output stage is zero when said two inputs have therebetween a specific voltage difference;
- c) providing a biasing stage which has a characteristic dependent on a manufacturing parameter, is electrically connected to said differential stage, provides a first biasing voltage for creating a second input voltage in said second input and provides a second biasing voltage for creating a first input voltage in said first input in order that said two input voltages have therebetween said specific voltage difference independent of said manufacturing parameter;
- and
- d) providing a bias-compensating circuit electrically connected to said biasing stage for providing a bias current which is independent from said output of said output stage for compensating said second biasing voltage so as to provide said specific voltage difference, wherein said bias-compensating circuit includes:
- a fixed biasing current circuit for providing a fixed biasing current;
- and
- a variable current circuit electrically connected to said fixed biasing current circuit for providing a manufacturing parameter-dependent current.
5 more elements
Dependencies are inferred from the claim text.