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US 5,706,006 AGranted
Operational amplifier incorporating current matrix type digital-to-analog converter
AssigneeNEC Corporation
InventorShigeo Hattori
Life of this patent
Estimating the term…
Abstract
In a digital-to-analog converter including a plurality of constant current sources, a plurality of first current switch elements connected between the constant sources and a first output terminal, and a plurality of second current switch elements connected between the constant current sources and a second output terminal, a reference voltage of the constant current sources is generated by an operational amplifier. The operational amplifier is disabled in response to a current control signal to turn OFF all the constant current sources.
Claims14
A digital-to-analog converter comprising:
- first and second power supply terminals;
- first and second output terminals;
- a plurality of constant current sources connected to said first power supply terminal;
- a plurality of first current switching elements, each connected between one of said constant current sources and said first output terminal;
- a plurality of second current switching elements, each connected between one of said constant current sources and said second output terminal;
- means for supplying a plurality of first signals to said first current switching elements;
- means for supplying a plurality of second signals to said second current switching elements;
- an operational amplifier for generating a first reference voltage and applying it to said constant current sources;
- means for providing a second reference voltage to a first input of said operational amplifier;
- feedback means for providing a feedback voltage of an output of said operational amplifier to a second input of said operational amplifier;
- and
- means for disabling said operational amplifier in response to a current control signal to turn OFF all said constant current sources.
9 more elements
A digital-to-analog converter comprising:
- first and second power supply terminals;
- first and second output terminals;
- a plurality of constant current sources connected to said first power supply terminal;
- a plurality of first current switching elements, each connected between one of said constant current sources and said first output terminal;
- a plurality of second current switching elements, each connected between one of said constant current sources and said second output terminal;
- means for supplying a plurality of input signals to said first current switching elements;
- means for supplying a plurality of second signals to said second current switching elements;
- a voltage divider, connected between said first and second power supply terminals, for supplying a definite voltage to said second current switching elements;
- a switching means, included in said voltage divider, for cutting OFF a current path between said first and second power supply terminals within said voltage divider in response to a current control signal;
- an operational amplifier for generating a first reference voltage and applying it to said constant current sources;
- means for providing a second reference voltage to a first input of said operational amplifier;
- feedback means for providing a feedback voltage of an output of said operational amplifier to a second input of said operational amplifier;
- and
- means for disabling said operational amplifier in response to said current control signal to turn OFF all said constant current sources.
11 more elements
Dependencies are inferred from the claim text.