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US 3,943,380 AGranted
Keyed comparator
AssigneeRCA Corporation
InventorsDavid Keith Morgan, Robert Charles Heuner
Life of this patent
Estimating the term…
Abstract
In the "on" condition of the circuit, a current mirror supplies a constant current to a comparator, a voltage divider circuit supplies a reference voltage to one input terminal of the comparator, and the input voltage to be compared to the reference voltage is applied to the other input terminal of the comparator. In the "off" condition of the circuit, the current mirror, the comparator and the voltage divider circuit are all cut off to reduce to substantially zero the power consumption of the circuit.
Claims10
In combination:
- two terminals across which an operating voltage may be applied;
- reference voltage establishing means comprising a voltage divider and a switch connected in series between said terminals;
- a current amplifier comprising input current path means, including a switch in series in said path means, said path means connected between one of said terminals serving as the input terminal of said amplifier and the other of said terminals serving as the common terminal of said amplifier, and output current path means connected between said common terminal and the output terminal of said current amplifier, said switch, when open, serving to terminate the flow of current between said input terminal and said common terminal of said amplifier and thereby to terminate also the flow of current between said common terminal and said output terminal of said amplifier;
- a comparator comprising a differential amplifier having a common terminal, an output terminal, and two signal input terminals, said common terminal of said comparator connected to said output terminal of said current amplifier, one of said input terminals connected to a point along said voltage divider and the second input terminal for receiving a voltage which may vary to values greater and less than that at said point along said voltage divider;
- and
- means coupled to said switch of said reference voltage establishing means and to said switch of said current amplifier for concurrently closing and opening these switches.
3 more elements
A keyed bias circuit comprising, in combination:
- two terminals between which an operating voltage may be applied;
- two metal oxide semiconductor transistors of opposite channel conductivity types, each having a gate electrode and a conduction path, said conduction paths connected in series between said two terminals and said gate electrodes connected to a control terminal;
- means for applying voltage levels to said control terminal for switching said transistors between conducting and non-conducting states;
- a voltage divider connected across the conduction path of one of said transistors and having an output voltage tap, said divider having a resistance which is much higher than that of the conduction path of the other of said transistors;
- and a circuit connected to said tap having an input resistance which is much much higher than the resistance of said voltage divider.
2 more elements
A comparator system comprising, in combination:
- a first current mirror having a common, an input, and an output terminal;
- a pair of transistors, each having an input, an output and a control electrode, said input electrodes connected to a common terminal, one output electrode connected to the input terminal of the current mirror, the other output electrode connected to the output terminal of the current mirror, and said control electrodes serving as the signal input terminals of said comparator;
- a second current mirror having a common, an input and an output electrode, said output electrode connected to the common terminal to which said input electrodes are connected;
- first and second operating voltage terminals, the first connected to the common terminal of the first current mirror and the second connected to the common terminal of the second current mirror;
- means for coupling the input terminal of said second current mirror to said first operating voltage terminal and
- wherein said second current mirror comprises a first field-effect transistor of one channel conductivity type having a conduction path through which the input current of said second current mirror flows, connected between the input and common terminals of said current mirror, a second field-effect transistor of the same channel conductivity type having a conduction path in parallel with that of said first field-effect transistor, wherein said means for coupling comprises a third field-effect transistor of opposite channel conductivity type to said first and second transistors having a conduction path in series between said input terminal and said first operating voltage terminal, and having a control electrode connected to the control electrode of said second transistor, and a fourth field-effect transistors of the same channel conductivity type as said first transistor having a conduction path connected between the common and output terminals of said second current mirror and having a control electrode connected, in common, to the control electrode of said first transistor and the input terminal of said second current mirror.
3 more elements
In combination:
- first and second field-effect transistors of opposite channel conductivity types, each having a conduction path and a control electrode, said conduction paths connected in series between two operating voltage terminals and said control electrodes connected to a control terminal;
- a resistive voltage divider connected across the conduction path of the first of said transistors;
- means coupled to said control terminal for applying voltage levels thereto for switching said first transistor on and said second transistor off and vice versa;
- a field-effect transistor comparator circuit having two input terminals, one at the control electrode of a third field effect transistor and the other at the control electrode of a fourth field-effect transistor;
- a tap on said voltage divider connected to one of said input terminals;
- and
- means for applying a voltage to be compared with that at said tap to said other input terminal.
4 more elements
Dependencies are inferred from the claim text.