Voltage reference circuits

• US 4,088,941 A
• Filed: 10/05/1976
• Issued: 05/09/1978
• Est. Priority Date: 10/05/1976
• Status: Expired due to Term

• Current Assignee: RCA Corporation (General Electric Company)
• Original Assignee: RCA Corporation (General Electric Company)
• Inventors: Wheatley, Carl Franklin Jr.
• Primary Examiner(s): Pellinen, A. D.
• Application Number:
  US05/729,766
• Time in Patent Office: 581 Days
• Field of Search: 323/1, 323/4, 323/8, 323/19, 323/22 T, 330/17, 330/22, 330/23, 330/25, 330/30 D, 330/40, 330/257, 330/256, 330/296, 330/297
• US Class Current: 323/226
• CPC Class Codes: G05F 1/613 using semiconductor devices in parallel with the load as final control devices G05F1/461 takes precedence
• CPC Class Codes: G05F 3/265 using bipolar transistors only

Abstract

A first reference voltage which exhibits a negative coefficient of change with temperature is developed as an offset potential across a forward-biased semiconductor junction or a series string of such junctions operated at an absolute temperature T. A second reference voltage which varies in linear proportion to the absolute temperature T is additively combined with the first reference voltage to simulate a higher density of forward current flow through the semiconductor junctions.

Claims

1. A voltage reference circuit comprising:

first and second terminals between which reference voltage is to appear in response to applied current;

a resistive element;

at least one semiconductor diode means operated at at absolute temperature T and connected in a serial combination with said resistive element;

means applying a substantially fixed portion of any potential appearing between said first and said second terminals across said serial combination to forward-bias each said semiconductor diode means and thereby cause it to exhibit an offset potential with a negative-temperature coefficient;

means responsive to the potential drop across said resistive element due to said applied current being in excess of a threshold potential, which threshold potential is linearly proportionally related to said absolute temperature T, to provide an error signal directly related to said excess; and

means responsive to said error signal for shunt regulating the portion of said applied current flowing through said serial combination.

2. A voltage reference circuit as claimed in claim 1 wherein said means to provide an error signal comprises:

first and second transistors of the same conductivity type, being operated at an absolute temperature substantially equal to T, having respective base electrodes between which said resistance is connected, having respective emitter electrodes joined at an interconnection, and having respective collector electrodes;

a first current amplifier having input and common and output terminals, the collector electrode of said first transistor being connected to the input terminal of said first current amplifier, and the collector electrode of said second transistor and the output terminal of said first current amplifier being connected to a circuit node at which said error signal obtains; and

a source of current, connected between the common terminal of said first current amplifier and the interconnection at which the emitter electrodes of said first and said second transistors join.

3. A voltage reference circuit as claimed in claim 2 wherein said means for shunt regulating comprises:

a second current amplifier having an input terminal connected to said circuit node at which said error signal obtains, and having output and common nodes connected to separate ones of said first and said second terminals to complete a degenerative feedback loop.

4. A voltage reference circuit as set forth in claim 1 wherein each said semiconductor diode means is a self-biased transistor.

5. A voltage reference circuit comprising:

a conduction path between first and second nodes through at least one semiconductor junction, each arranged to operate at a temperature substantially equal to T;

means applying a current to said conduction path to forward bias each said semiconductor junction therein and thereby develop an offset potential across each said semiconductor junction;

first and second transistors of the same conductivity type, having respective base-emitter junctions in 1;

m ratio, having respective base and emitter and collector electrodes, being arranged to operate at respective temperatures each substantially equal to T, and being connected together in emitter-coupled differential amplifier configuration;

a current amplifier having input and output terminals between which a current gain of -g is exhibited, and having a common terminal, m and g being positive numbers the product of which differs from unity;

means connecting said current amplifier as a balanced to single-ended signal converter for the direct collector currents of said first and said second transistors including a direct current conductive connection of the collector electrode of said first transistor to the input terminal of said current amplifier and direct current conductive connections of the collector electrode of said second transistor and of the output terminal of said current amplifier to a third node;

a direct coupled degenerative feedback connection from said third node to the base electrodes of said first and said second transistors for reducing the imbalance between the current flows into and out of said third node, thereby to cause a difference potential between the base electrodes of said first and second transistor;

means for deriving a potential proportional to said differential potential; and

means for summing each said offset potential, said difference potential and said potential proportional to said difference potential together to provide an output reference voltage.

6. A shunt potential regulator circuit for providing a standard potential substantially constant despite changes in the temperature of elements in said shunt potential regulator circuit, which shunt potential regulator circuit comprises:

first and second terminals for application of operating current, also between which terminals said standard potential is provided;

resistive potential divider means having an input circuit and an output circuit;

semiconductor diode means in a first series connection with the input circuit of said resistive potential divider means between said first and said second terminals;

first and second transistors of the same conductivity type, having respective base electrodes between which the output circuit of said resistive potential divider means is connected, having respective emitter electrodes directly connected together at an interconnection, having respective base-emitter junctions with respective areas in 1-to-m ratio, having respective collector electordes, and being operated at essentially the same temperature as said semiconductor diode means,

a source of combined emitter bias currents for said first and said second transistors, said source being connected between said first terminal and said interconnection of their emitter electrodes;

a first amplifier having input and output circuits to which the collector electrodes of said second and said first transistors are respectively connected, said first amplifier exhibiting a predetermined constant current gain of -g between its input and output circuits, m and g being positive numbers the product of which differs from unity;

a second amplifier having an input circuit to which the output circuit of said first amplifier is direct coupled and having an output circuit connected between said first and said second terminals to complete a degenerative feedback connection of the foregoing elements for regulating the potential between said first and said second terminals.

7. In combination:

a current supply having first and second terminals, one of which is negative and the other positive;

first and second resistances in constant proportion with each other despite change in their operating temperatures;

diode means having and anode an cathode for responding to current flow between its anode and cathode and to an absolute temperature T with a negative-temperature-coefficient potential between its cathode and anode, which negative-temperature coefficient potential is proportional to the offset potential of a semiconductor junction exposed to such current and temperature conditions;

a serial connection of said first and said second resistances and said diode means between the positive and negative terminals of said current supply, the anode and cathode of said diode means disposed respectively closer to the positive terminal of said current supply and closer to the negative terminal of said current supply;

first and second transistors, being of the same basic semiconductor material and of the same conductivity type, being operated at respective absolute temperatures, each substantially equal to T, having respective base and emitter and collector electrodes, having their respective base electrodes connected to opposite ends of said first resistance, and having respective base-emitter junctions with respective areas in m;

1 ratio, m being a positive number;

a current amplifier having an input terminal to which the collector electrode of said first transistor is galvanically coupled, having output and common terminals, and exhibiting a current gain of -g between its input and output terminals, g being a positive number which when multiplied by m yields a product different from unity;

means for applying current to an interconnection of the emitter electrodes of said first and second transistors in a poling to forward-bias the base-emitter junctions of said first and said second transistors;

means for supplying a response current linearly related to the sum of currents galvanically coupled thereto from the collector electrode of said second transistor and from the output terminal of said current amplifier, said response current applied across said serial connection of said first and said second resistances and said diode means to regulate the potential across said first resistance to reduce said response current by degenerative feedback.