Voltage reference and voltage level sensing circuit

Claim 2

A voltage level sensing circuit comprising in combination: first and second junction points for applying therebetween a source of potential whose amplitude is to be sensed; first and second insulated-gate field-effect transistors of first and second conductivity type, respectively; each transistor having a drain, a source and a gate electrode, and each transistor having a threshold voltage defined as the minimum gate-to-source potential that must be applied to initiate conduction in the drain-source path; an output point for producing thereat a signal indicative of whether the amplitude of said source potential is greater or less than the sum of the threshold voltages of said first and second transistors; means connecting the gate and drain of said first transistor together and to the gate of said second transistor; means connecting the source of said first transistor to one of said first and second junction points for generating a potential drop equal to the threshold voltage of said first transistor between said one junction point and the gate electrode of said second transistor; and means connecting the source of said second transistor to the other one of said junction points and the drain of said second transistor to said output point.

Claim 3

The combination as claimed in claim 1 further including current generating means connected to the drain and gate of said first transistor for providing a current path for the drain-source path of said first transistor.

Claim 4

The combination as claimed in claim 2 wherein said current generating means is a resistor connected between said first transistor and the other one of said junction points.

Claim 5

The combination as claimed in claim 3 further including a complementary inverter comprising third and fourth transistors of first and second conductivity type, respectively, each transistor having a gate, a drain and a source electrode; means connecting the gate electrodes of said third and fourth transistors in common to said output point; an output terminal for producing an output signal which is an inverteD and amplified version of the signal at said output point; means connecting the drain electrodes of said two transistors in common and to said output terminal ; and means for connecting the source electrodes of said complementary transistors to opposite terminals of a source of operating potential.

Claim 6

The combination as claimed in claim 3 wherein said source of potential has an amplitude which varies with time; and wherein the potential applied between the gate and source electrodes of said second transistor is equal to the value of the input signal minus the threshold voltage drop of said first transistor.

Claim 7

The combination as claimed in claim 3 wherein said transistors are insulated-gate field-effect transistors of the enhancement type.

Claim 8

The combination comprising: first and second transistors, each having a source region and a drain region spaced apart to form a channel; the regions of said first transistor being of first conductivity type and the regions of said second transistors being of second conductivity type, each transistor having a gate electrode separated from said channel by an insulating layer formed in common on both transistors; each transistor being characterized by a threshold voltage defined as the minimum gate-to-source potential that must be applied for conduction in the drain-source path; said threshold voltage depending in part on surface charges in the insulating layer wherein the threshold voltage of one of said transistors is increased by said surface charge and the threshold voltage of the other transistor is decreased a like amount by said surface charge; first and second junction points; means for applying a source of potential between said junction points; means connecting the gate and drain of one of said two transistors in common and to the gate of the other one of said two transistors; means connecting the source electrodes of said first and second transistors to a different one of said junction points for summing their threshold voltages therebetween and effectively cancelling the effect of surface charge in the insulating layer; and output load means connected to the drain region of the other one of said transistors for producing an output signal as a function of the amplitude of the source of potential being greater than or less than the sum of the threshold voltages of said first and second transistors.

Claim 9

The combination comprising: first and second transistors, each having a source region and a drain region spaced apart to form a channel; the regions of said first transistor being of first conductivity type and the regions of said second transistors being of second conductivity type, each transistor having a gate electrode separated from said channel by an insulating layer formed in common on both transistors; each transistor being characterized by a threshold voltage defined as the minimum gate-to-source potential that must be applied for conduction in the drain-source path; said threshold voltage depending in part on surface charges in the insulating layer wherein the threshold voltage of one of said transistors is increased by said surface charge and the threshold voltage of the other transistor is decreased a like amount by said surface charge; first and second junction points; means for applying a source of potential between said junction points; means connecting the gate and drain of one of said two transistors in common and to the gate of the other one of said two transistors; means connecting the source electrodes of said first and second transistors to a different one of said junction points for summing their threshold voltages therebetween and effectively cancelling the effect of surface charge in the insulating layer; and output load means connected to the drain region of the other one of said transistors for producing an output signal as a function of the amplitude of the source of potential being greater than or less than the sum of the threshold voltages of said first and second transistors.

Claim 10

In an integrated circuit comprised of insulated-gate field-effect transistors of first and second conductivity type; each transistor being characterized by a threshold voltage which is dependent in part on surface charges which increase the threshold voltage of one type of transistor by a given amount and decrease the threshold voltage of the other type of transistors by substantially the same amount, an improved voltage reference circuit comprising: first and second junction points; two transistors, one of said first conductivity type and the other one of said second conductivity type, each transistor having a gate, a drain and a source electrode; means connecting the gate and drain of one of said two transistors together and to the gate of the other transistor; and means connecting the source of said one transistor to said first junction point and the source of the other one of said two transistors to said second junction point for summing the threshold voltages of the two transistors between said two junction points and producing therebetween a source of reference potential.

Claim 11

In an integrated circuit comprised of insulated-gate field-effect transistors of first and second conductivity type; each transistor being characterized by a threshold voltage which is dependent in part on surface charges which increase the threshold voltage of one type of transistor by a given amount and decrease the threshold voltage of the other type of transistors by substantially the same amount, an improved voltage reference circuit comprising: first and second junction points; two transistors, one of said first conductivity type and the other one of said second conductivity type, each transistor having a gate, a drain and a source electrode; means connecting the gate and drain of one of said two transistors together and to the gate of the other transistor; and means connecting the source of said one transistor to said first junction point and the source of the other one of said two transistors to said second junction point for summing the threshold voltages of the two transistors between said two junction points and producing therebetween a source of reference potential.

Claim 12

In integrated circuits which include transistors of two conductivity types and in which the sum of the threshold voltages of two transistors of first and second conductivity type on one integrated circuit is substantially equal to the sum of the threshold voltages of two transistors of first and second conductivity type on another integrated circuit made in the same manner and by the same process, a stable voltage reference circuit comprising, in combination: a pair of terminals across which a voltage is to be applied; a series circuit connected between said terminals comprising a transistor of said one conductivity type connected to operate as a diode, connected in series with an impedance; and a second circuit comprising a transistor of said second conductivity type having a control electrode and a conduction path whose conductivity is controlled by the potential applied to said control electrode, and a load in series with said conduction path, said control electrode being connected to an intermediate point along said series circuit, and said conduction path being connected, at the end thereof not connected to said load, to one of said pair of terminals.

Claim 13

In integrated circuits which include transistors of two conductivity types and in which the sum of the threshold voltages of two transistors of first and second conductivity type on one integrated circuit is substantially equal to the sum of the threshold voltages of two transistors of first and second conductivity type on another integrated circuit made in the same manner and by the same process, a stable voltage reference circuit comprising, in combination: a pair of terminals across which a voltage is to be applied; a series circuit connected between said terminals comprising a transistor of said one conductivity type connected to operate as a diode, connected in series with an impedance; and a second circuit comprising a transistor of said second conductivity type having a control electrode and a conduction path whose conductivity is controlled by the potential applied to said control electrode, and a load in series with said conduction path, said control electrode being connected to an intermediate point along said series circuit, and said conduction path being connected, at the end thereof not connected to said load, to one of said pair of terminals.

Claim 14

In a circuit as set forth in claim 9, both of said transistors being field-effect transistors having a conduction path and a control electrode and said transistor connected as a diode including a direct connection between its control electrode and one end of its conduction path.

Claim 15

In a circuit as set forth in claim 9, said impedance and said load comprising resistors.

Claim 16

In a circuit as set forth in claim 9, the circuit comprising the load in series with the conduction path of the second circuit being also connected between said pair of terminals.

Claim 17

In a circuit which includes transistors of two different conductivity types and in which the sum of the threshold voltage of a transistor of one conductivity type and the threshold voltage of a transistor of second conductivity type is a reproducible and constant level, a stable voltage reference circuit comprising, in combination: a pair of terminals across which a voltage is to be applied: two field-effect transistors of opposite conductivity type, each having a drain electrode, a gate electrode, and a source electrode; said two transistors being connected together at their gate electrodes, the source electrode of one transistor being connected to one of said terminals and the source electrode of the other transistor being connected to the other of said terminals; a direct connection between the gate electrode and drain electrode of one of said transistors; and output load means connected to the drain electrode of the other one of said two transistors for producing a current therethrough when the amplitude of the voltage applied across said pair of terminals exceeds the sum of the threshold voltages of said two transistors.

Claim 18

In a circuit which includes transistors of two different conductivity types and in which the sum of the threshold voltage of a transistor of one conductivity type and the threshold voltage of a transistor of second conductivity type is a reproducible and constant level, a stable voltage reference circuit comprising, in combination: a pair of terminals across which a voltage is to be applied: two field-effect transistors of opposite conductivity type, each having a drain electrode, a gate electrode, and a source electrode; said two transistors being connected together at their gate electrodes, the source electrode of one transistor being connected to one of said terminals and the source electrode of the other transistor being connected to the other of said terminals; a direct connection between the gate electrode and drain electrode of one of said transistors; and output load means connected to the drain electrode of the other one of said two transistors for producing a current therethrough when the amplitude of the voltage applied across said pair of terminals exceeds the sum of the threshold voltages of said two transistors.