Low voltage reference circuit

Claim 2

A reference voltage circuit for establishing a potential difference between first and second terminals comprising, in combination: a first stack of one or more substantially identical semiconductor elements connected in series in the forward direction between said first terminal and a point of reference potential, a second stack comprising a like number of semiconductor elements substantially identical to each other and connected in series in the forward direction between said second terminal and said point of reference potential, each of said semiconductor elements of said first and second stacks having a nonlinear current versus voltage characteristic; and means for applying first and second varying currents to said first and second terminals, which currents remain in a fixed ratio relative to each other independent of variations in their actual magnitude, whereby the elements of said first stack operate at a different point on their characteristic as compared with the elements of said second stack, resulting in a desired potential difference between said terminals.

Claim 3

A reference voltage circuit as defined in clAim 1 wherein said current applying means comprises a source of supply voltage having a magnitude that varies over a particular range, said currents maintaining said fixed ratio despite variations within said range.

Claim 4

A reference voltage circuit as defined in claim 1 wherein said semiconductor elements are diode-connected integrated circuit transistors formed on a common substrate.

Claim 5

A reference voltage circuit as defined in claim 3 wherein the potential difference between said first and second terminals is determined in accordance with the following equation: Delta V n (KT/q) 1n (I1/I2) where k Boltzmann''s constant, T temperature in degrees Kelvin, q charge on an electron, n number of elements per stack, and I1 and I2 currents through said first and second stacks, respectively.

Claim 6

A reference voltage circuit for establishing a potential difference between first and second terminals comprising, in combination: a first voltage reference comprising a first stack of substantially identical asymmetrically conducting semiconductor elements connected in series in the forward direction between said first terminal and a point of reference potential, each of said semiconductor elements having a nonlinear current versus voltage characteristic; a second voltage reference comprising a like stack of elements connected in series in the forward direction between said second terminal and said point of reference potential; and means for applying first and second currents of different value to said first and second terminals from a source whose voltage varies over a particular range, said currents maintaining a fixed ratio relative to each other over said range, whereby the elements of said first stack operate at a different point on their characteristic as compared with the elements of said second stack resulting in a desired potential difference between said terminals.

Claim 7

A reference voltage circuit for establishing a potential difference between first and second terminals comprising, in combination: a first voltage reference comprising a first stack of substantially identical asymmetrically conducting semiconductor elements connected in series in the forward direction between said first terminal and a point of reference potential, each of said semiconductor elements having a nonlinear current versus voltage characteristic; a second voltage reference comprising a like stack of elements connected in series in the forward direction between said second terminal and said point of reference potential; and means for applying first and second currents of different value to said first and second terminals from a source whose voltage varies over a particular range, said currents maintaining a fixed ratio relative to each other over said range, whereby the elements of said first stack operate at a different point on their characteristic as compared with the elements of said second stack resulting in a desired potential difference between said terminals.

Claim 8

A reference voltage circuit as defined in claim 5 wherein said semiconductor elements are diode-connected integrated circuit transistors formed on a common substrate.

Claim 9

A reference voltage circuit as defined in claim 5 wherein the potential difference between said first and second terminals is determined in accordance with the following equation: Delta V n (kT/q) 1n (I1/I2) where k Boltzmann''s constant, T temperature in degrees Kelvin, q charge on an electron, n number of elements per stack, and I1 and I2 currents through said first and second stacks, respectively.

Claim 10

A reference voltage circuit for establishing a relatively small potential difference between first and second terminals comprising, in combination: a common substrate; a first plurality of substantially matching diodes formed on said substrate and connected in series in the forward direction between said first terminal and a point of reference potential; a like plurality of diodes formed on said substrate and connected in series in the forward direction between said second terminal and said point of reference potential; and means for applying first and second varying currents of different value to said first and second terminals, said currents maintaining a fixed ratio with respect to each other independent of variations in their actual magnitude, said ratio determining the potential difference between said first and second terminals.

Claim 11

A reference voltage circuit for establishing a relatively small potential difference between first and second terminals comprising, in combination: a common substrate; a first plurality of substantially matching diodes formed on said substrate and connected in series in the forward direction between said first terminal and a point of reference potential; a like plurality of diodes formed on said substrate and connected in series in the forward direction between said second terminal and said point of reference potential; and means for applying first and second varying currents of different value to said first and second terminals, said currents maintaining a fixed ratio with respect to each other independent of variations in their actual magnitude, said ratio determining the potential difference between said first and second terminals.

Claim 12

A reference voltage circuit as defined in claim 8 wherein said current applying means comprises a source whose voltage varies over a particular range, said currents maintaining said fixed ratio over said range.

Claim 13

A reference voltage circuit as defined in claim 9 wherein the potential difference between said first and secoNd terminals is determined in accordance with the following equation: Delta V n (kT/q) 1n (I1/I2) where k Boltzmann''s constant, T temperature in degrees Kelvin, q charge on an electron, n number of elements per stack, and I1 and I2 currents through said first and second stacks, respectively.

Claim 14

A voltage detection circuit adapted to provide a desired output signal in response to the attainment of a predetermined threshold by a fluctuating input signal, comprising: a difference circuit having first and second input terminals and an output terminal, said difference circuit being adapted to provide said desired output signal when the potential at one of said input terminals attains a predetermined relationship with respect to the potential at the remaining one of said input terminals; a first voltage reference comprising a first stack of one or more substantially identical semiconductor elements formed as part of an integrated circuit and connected in series in the forward direction; a second voltage reference comprising a second stack of one or more substantially identical semiconductor elements formed as part of an integrated circuit and connected in series in the forward direction; means for applying first and second varying currents to said first and second reference stacks, which currents remain in a fixed ratio relative to each other independent of variations in their actual magnitude, said fixed ratio establishing a voltage difference between said first and second voltage references, said difference having a predeterminable value related to the voltage to be detected; means for coupling said fluctuating input signal in circuit with one of said voltage references and said one input terminal; and means for coupling the other of said voltage references in circuit with said remaining one of said input terminals, whereby said desired signal is provided at the output of said difference circuit when said fluctuating input signal attains said predetermined threshold to cause the potential at said one input terminal to attain said predetermined relationship with respect to the potential at said remaining one of said input terminals.

Claim 15

A voltage detection circuit adapted to provide a desired output signal in response to the attainment of a predetermined threshold by a fluctuating input signal, comprising: a difference circuit having first and second input terminals and an output terminal, said difference circuit being adapted to provide said desired output signal when the potential at one of said input terminals attains a predetermined relationship with respect to the potential at the remaining one of said input terminals; a first voltage reference comprising a first stack of one or more substantially identical semiconductor elements formed as part of an integrated circuit and connected in series in the forward direction; a second voltage reference comprising a second stack of one or more substantially identical semiconductor elements formed as part of an integrated circuit and connected in series in the forward direction; means for applying first and second varying currents to said first and second reference stacks, which currents remain in a fixed ratio relative to each other independent of variations in their actual magnitude, said fixed ratio establishing a voltage difference between said first and second voltage references, said difference having a predeterminable value related to the voltage to be detected; means for coupling said fluctuating input signal in circuit with one of said voltage references and said one input terminal; and means for coupling the other of said voltage references in circuit with said remaining one of said input terminals, whereby said desired signal is provided at the output of said difference circuit when said fluctuating input signal attains said predetermined threshold to cause the potential at said one input terminal to attain said predetermined relationship with respect to the potential at said remaining one of said input terminals.

Claim 16

A voltage detection circuit as defined in claim 11 wherein said current applying means comprises a source of supply voltage having a magnitude that varies over a particular range, said currents maintaining said fixed ratio despite variations within said range.

Claim 17

A voltage detection circuit as defined in claim 11 wherein said first and second stacks comprise a like number of substantially identical diode-connected integrated circuit transistors formed on a common substrate.

Claim 18

A voltage detection circuit as defined in claim 13 wherein the voltage difference between said first and second voltage references is determined in accordance with the following equation: Delta V n (kT/q) 1n (I1/I2) where k Boltzmann''s constant, T temperature in degrees Kelvin, q charge on an electron, n number of elements per stack, and I1 and I2 currents through said first and second stacks, respectively.

Claim 19

A voltage detection circuit as defined in claim 11 wherein the reference level of said other of said voltage references varies in response to the condition at said output terminal of said difference circuit.

Claim 20

A voltage detection circuit adapted to provide a desired output signal in response to the attainment of a predetermined threshold by a fluctuating input signal having a relatively low magnitude of potential, comprising: a difference circuit having first and second input terminals and an output terminal; a first voltage reference comprising a first stack of onE or more substantially identical asymmetrically conducting semiconductor elements formed on a common substrate and connected in series in the forward direction, each of said elements having a nonlinear current versus voltage characteristic; a second voltage reference comprising a like stack of elements similarly formed and connected; means for applying first and second varying currents of different value to said first and second reference stacks, which currents remain in a fixed ratio relative to each other idependent of variations in their actual magnitude, whereby the elements of said first stack operate at a different point on their characteristic as compared with the elements of said second stack resulting in a voltage difference between said first and second stacks equal to the voltage to be detected, said difference being small relative to the absolute voltage across either of said stacks; means for coupling said fluctuating input signal in circuit with one of said voltage references and one of said input terminals; and means for coupling the other of said voltage references in circuit with the other of said input terminals, whereby said desired signal is provided at the output of said difference circuit when said fluctuating input signal attains said predetermined threshold to cause the potential at said one input terminal to attain said predetermined relationship with respect to the potential at said other terminal.

Claim 21

A voltage detection circuit adapted to provide a desired output signal in response to the attainment of a predetermined threshold by a fluctuating input signal having a relatively low magnitude of potential, comprising: a difference circuit having first and second input terminals and an output terminal; a first voltage reference comprising a first stack of onE or more substantially identical asymmetrically conducting semiconductor elements formed on a common substrate and connected in series in the forward direction, each of said elements having a nonlinear current versus voltage characteristic; a second voltage reference comprising a like stack of elements similarly formed and connected; means for applying first and second varying currents of different value to said first and second reference stacks, which currents remain in a fixed ratio relative to each other idependent of variations in their actual magnitude, whereby the elements of said first stack operate at a different point on their characteristic as compared with the elements of said second stack resulting in a voltage difference between said first and second stacks equal to the voltage to be detected, said difference being small relative to the absolute voltage across either of said stacks; means for coupling said fluctuating input signal in circuit with one of said voltage references and one of said input terminals; and means for coupling the other of said voltage references in circuit with the other of said input terminals, whereby said desired signal is provided at the output of said difference circuit when said fluctuating input signal attains said predetermined threshold to cause the potential at said one input terminal to attain said predetermined relationship with respect to the potential at said other terminal.

Claim 22

A voltage detection circuit as defined in claim 16 wherein all of said semiconductor elements are diode-connected integrated circuit transistors formed on a common substrate.

Claim 23

A voltage detection circuit as defined in claim 17 wherein the voltage difference between said first and second voltage references is determined in accordance with the following equation: Delta V n (kT/q) 1n (I1/I2) where k Boltzmann''s constant, T temperature in degrees Kelvin, q charge on an electron, n number of diodes per stack, and I1 and I2 currents through said first and second stacks, respectively.

Claim 24

A voltage detection circuit as defined in claim 16 further comprising, feedback means coupled between said output terminal of said difference circuit and said other voltage reference, said feedback means operating in response to the condition at said output terminal to cause the reference level of said other voltage reference to decrease as the signal at said output terminal approaches said desired output signal.

Claim 25

A threshold detection circuit adapted to provide a desired output signal in response to the attainment of a predetermined threshold by a fluctuating input signal of relatively small magnitude comprising, in combination: a source of supply voltage having a magnitude that varies over a particular range; a difference circuit having first and second input terminals and an output terminal, said difference circuit being adapted to provide said output signal when the potential at one of said input terminals attains a predetermined relationship with respect to the potential at the remaining one of said input terminals; a first voltage reference comprising a first stack of one or more substantially identical diode-connected integrated circuit transistors connected in series in the forward direction, and a second voltage reference comprising a like stack of transistors similarly connected, all of said transistors formed on a common substrate; means for applying first and second currents of different value to said first and second reference stacks from said source of supply voltage, said currents maintaining a fixed ratio relative to each other over said range, said ratio establishing a voltage difference between said first and second voltage reference stacks equal to the voltage to be detected, said difference being small relative to the absolute Voltage across either of said stacks; means for coupling said fluctuating input signal in circuit with one of said voltage references and said one input terminal; and means for coupling the other of said voltage references in circuit with said remaining one of said input terminals, whereby said desired output signal is provided at the output of said difference circuit when said fluctuating input signal attains said predetermined threshold to cause the potential at said one input terminal to attain said predetermined relationship with respect to the potential at said remaining input terminal.

Claim 26

A threshold detection circuit adapted to provide a desired output signal in response to the attainment of a predetermined threshold by a fluctuating input signal of relatively small magnitude comprising, in combination: a source of supply voltage having a magnitude that varies over a particular range; a difference circuit having first and second input terminals and an output terminal, said difference circuit being adapted to provide said output signal when the potential at one of said input terminals attains a predetermined relationship with respect to the potential at the remaining one of said input terminals; a first voltage reference comprising a first stack of one or more substantially identical diode-connected integrated circuit transistors connected in series in the forward direction, and a second voltage reference comprising a like stack of transistors similarly connected, all of said transistors formed on a common substrate; means for applying first and second currents of different value to said first and second reference stacks from said source of supply voltage, said currents maintaining a fixed ratio relative to each other over said range, said ratio establishing a voltage difference between said first and second voltage reference stacks equal to the voltage to be detected, said difference being small relative to the absolute Voltage across either of said stacks; means for coupling said fluctuating input signal in circuit with one of said voltage references and said one input terminal; and means for coupling the other of said voltage references in circuit with said remaining one of said input terminals, whereby said desired output signal is provided at the output of said difference circuit when said fluctuating input signal attains said predetermined threshold to cause the potential at said one input terminal to attain said predetermined relationship with respect to the potential at said remaining input terminal.

Claim 27

A threshold detection circuit as defined in claim 20 wherein said current applying means further comprises first and second resistances formed on said common substrate and connected in series with the first and second stacks of said first and second voltage references, respectively, the resistive ratio of said resistances determining said fixed current ratio.

Claim 28

A threshold detection circuit as defined in claim 21 wherein the voltage difference between said first and second voltage references is determined in accordance with the following equation: Delta V n (kT/q) 1n (I1/I2) where k Boltzmann''s constant T temperature in degrees Kelvin, q charge on an electron, n number of diodes per stack, and I1 and I2 currents through said first and second stacks, respectively.

Claim 29

A threshold detection circuit as defined in claim 21 further comprising feedback means coupled between said output terminal of said difference circuit and said other voltage reference, said feedback means operating in response to the condition at said output terminal to cause the voltage across said other voltage reference to decrease as the signal at said output terminal approaches said desired output signal.