EP0264563B1 - Voltage regulator having a precision thermal current source - Google Patents

Voltage regulator having a precision thermal current source Download PDF

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Publication number
EP0264563B1
EP0264563B1 EP87111725A EP87111725A EP0264563B1 EP 0264563 B1 EP0264563 B1 EP 0264563B1 EP 87111725 A EP87111725 A EP 87111725A EP 87111725 A EP87111725 A EP 87111725A EP 0264563 B1 EP0264563 B1 EP 0264563B1
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EP
European Patent Office
Prior art keywords
transistor
current
coupled
emitter
base
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP87111725A
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German (de)
English (en)
French (fr)
Other versions
EP0264563A1 (en
Inventor
Byron G. Bynum
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Motorola Solutions Inc
Original Assignee
Motorola Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/915,481 external-priority patent/US4677368A/en
Priority claimed from US06/915,483 external-priority patent/US4683416A/en
Application filed by Motorola Inc filed Critical Motorola Inc
Publication of EP0264563A1 publication Critical patent/EP0264563A1/en
Application granted granted Critical
Publication of EP0264563B1 publication Critical patent/EP0264563B1/en
Anticipated expiration legal-status Critical
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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
    • G05F3/02—Regulating voltage or current
    • G05F3/08—Regulating voltage or current wherein the variable is dc
    • G05F3/10—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics
    • G05F3/16—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices
    • G05F3/20—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations
    • G05F3/30—Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities

Definitions

  • This invention relates to current supply circuits and, more particularly, to integrated circuits (IC) capable of producing currents having regulated magnitudes and predetermined temperature characteristics which are suitable to be used to produce a voltage regulator voltage the magnitude and temperature coefficient of which can be set.
  • IC integrated circuits
  • thermal current sources are in conjunction with other circuitry to provide a regulated output voltage having a known TC.
  • This thermal current can be utilized to produce a voltage across a resistor having a positive TC which is then placed in series with the negative TC base-to-emitter voltage of a NPN transistor to provide a zero TC output voltage.
  • These types of voltage regulators are sometimes referred to by those skilled in the art as bandgap voltage regulators.
  • Prior art voltage regulators commonly include a pair of transistors operated at different current densities.
  • the two transistors are interconnected with associated circuitry so as to develop a voltage therebetween that is proportional to the difference in the respective base-to-emitter voltages ( ⁇ V be ).
  • This difference voltage is used to set the current in the emitter of one of the transistors and has a positive temperature coefficient (TC).
  • TC positive temperature coefficient
  • the thermal emitter current is utilized to produce a voltage that varies directly with absolute temperature which, in turn, is combined with a negative TC voltage to produce a combined voltage having a substantially zero TC.
  • prior art regulators have significant advantages most, if not all, suffer from serious limitations. For instance, to prevent errors in the thermal current that may be caused by differences in the collector-to-emitter voltages of the two transistors, prior art regulators require complex feedback schemes to inhibit mismatch of the two devices. These schemes are not desirable in the design of integrated circuits as undue chip area is required. Additionally, the voltage level and temperature coefficient of the output regulated voltage of these prior art regulators can not be independently set but rather are determined by the magnitude of the difference voltage ⁇ V BE . Moreover, prior art regulators can not generate adjustable TC regulated voltages less than the value of a transistor V BE voltage.
  • a thermal current supply circuit comprising: first and second transistors having their bases coupled together and being operated at different predetermined current densities to produce a difference voltage between the emitters thereof having a predetermined positive temperature coefficient; a first resistor coupled to the emitter of said first transistor for sinking the current therefrom; a second resistor coupled to the emitter of said second transistor for sinking a portion of the current therefrom; a third transistor having its collector-emitter path coupled between the emitter of said second transistor and a circuit node (I out ); and feedback circuit means coupled to the collector of said second transistor and being responsive to said second transistor to provide a feedback signal to the base of said third transistor such that the latter sinks current from the emitter of said second transistor of a predetermined magnitude which is proportional to the difference voltage and inversely proportional to the value of said second resistor, said current flowing through said third transistor to the circuit node having said predetermined positive temperature coefficient.
  • An improved voltage regulator comprising a thermal current source in accordance with the invention.
  • the voltage regulator provides an output voltage that can be set to a predetermined voltage level and temperature coefficient.
  • Fig. 1 illustrates the basic components and interconnection of reference cell 12 of thermal current source 10.
  • Current source 10 is suited for providing fan out to multiple current sources such as NPN transistors 14, 16 and 18 coupled thereto at terminal 20.
  • the collectors of the current source transistors are connected to respective current utilization circuits 22, 24 and 26 each of which requires a current having a predetermined temperature characteristic that varies with absolute temperature.
  • Reference cell 12 of thermal current source 10 includes a pair of NPN transistors 28 and 30 the emitters of which are respectively coupled via resistors 32 and 34 to the base of NPN transistor 36.
  • the collector-emitter path of transistor 36 is coupled between the emitter of transistor 30 and negative supply conductor 38 to which negative or ground reference voltage -V is supplied.
  • Transistor 28 is connected as a diode having its collector and base interconnected to the base of transistor 30.
  • a pair of current sources 40 and 42 supply currents I1 and I2 to the collectors of transistors 28 and 30 respectively and are connected to power supply conductor 44 to which a positive operating voltage V cc is supplied.
  • buffer NPN transistor 46 which has its base coupled to the collector of transistor 30 and its collector-emitter path coupled between conductor 44 and output node 20 (to the base of transistor 36) in series with resistor 48 to negative supply conductor 38.
  • the concept of the present invention consists of (1) developing a difference voltage having a positive temperature coefficient (TC), (2) utilizing the difference voltage to set the current that flows in the collector of transistor 36 wherein the collector current has a magnitude that varies with absolute temperature, (3) utilizing the negative TC base-emitter voltage drop, V BE , of transistor 36 to develop a current having a negative TC through resistor 56, and (4) summing the two currents at node 62 to produce a combined voltage the value and temperature coefficient of which is controllable.
  • TC positive temperature coefficient
  • a difference voltage is produced in the present invention by operating transistors 28 and 30 at different current densities, which as understood, generates a positive difference voltage ⁇ V BE between the emitters of the two transistors.
  • transistor 28 is operated at a lower current density than transistor 30 by making its emitter area N times larger than the emitter area of transistor 30 (where N is a positive number) and setting I1 equal to I2. If resistor 32 equals resistor 34, the voltage developed across the base-emitter of transistor 28 and resistor 32 will equal the voltage developed across the base-emitter of transistor 30 and resistor 34.
  • transistor 28 since transistor 28 is operated at the lower current density its base-emitter voltage will be less than the base-emitter voltage of transistor 30 wherein at quiescence the aforementioned difference voltage is established between the emitters thereof. Initially, however, since transistor 28 sinks all of the current I1 and is operated as a diode it will set the voltage to bias transistor 30. As the emitter of transistor 30 is (1/N) times smaller than the emitter of transistor 28 the former will initially sink a collector current less than the magnitude of I2. This causes the collector voltage of transistor 30 to rise which turns on feedback transistor 46.
  • Transistor 46 will then source base current drive to transistor 36 thereby rendering it conductive to sink a current, I T , at its collector from the emitter of transistor 30 until the current flow through the latter equals the current I2, which is equal to I1.
  • I T current
  • the circuit feedback action produces the difference voltage ⁇ V BE between the emitters thereof. This establishes the current I T sank by transistor 36.
  • I T is a thermal current having a magnitude which can be controllably set by the value of R34 and which varies in direct relation to absolute temperature.
  • NPN transistor 46 provides feedback current to bias the base of transistor 36 to ensure that it sinks the correct collector current.
  • Transistor 46 also buffers the fan out base currents of current supply transistors 14, 16 and 18 from affecting the operation of transistors 28 and 30.
  • Resistor 48 is selected to sink a current greater than the sum of the currents flowing through resistors 32 and 34 to assure proper bias current in transistor 46.
  • transistor 16 has resistor 49 in its emitter path and transistor 18 is shown as having multi-emitters.
  • Thermal current source cell 12 is relatively independent to variations in the power supply voltage as the collector-emitter voltages of transistors 28 and 30 are well matched since the collector-base voltage of both transistors is substantially equal to zero.
  • Transistor 50 which has its collector emitter path coupled between power supply conductor 44 and the bases of transistors 28 and 30 and its base connected to current source 40, buffers the base currents to the latter transistors to reduce error between I1 and I2.
  • transistor 52 with its collector-emitter path connected between power supply conductor 44 and the base of transistor 46 and its base connected to current source 42, buffers the base current of transistor 46.
  • Fig. 3 shows a thermal current source 54 which provides an output current I out that has an adjustable temperature coefficient using the concepts disclosed above with respect to current source 10.
  • V BE has a positive TC and V BE36 has a negative TC
  • selection of the ratio of R34 to R56 can set the TC of I out either positive, negative or even zero. It is understood that V BE of transistor 36 is well controlled as the collector current thereof is known to be V BE /R34.
  • resistors 32 and 34 have been illustrated above as being interconnected to the base of transistor 36. However, it is apparent from the present disclosure that resistors 32 and 34 could also be interconnected at a common node to any source of reference potential as long as transistor 30 is inhibited from becoming saturated. It is also understood that transistor 52 could be used to buffer transistor 46 as illustrated in Fig. 2.
  • Fig. 4 illustrates voltage regulator 60 of the present invention which includes thermal current source 54 described above.
  • output node 62 is connected in series with additional resistor 64.
  • Transistor 52 which has its base-emitter coupled between the collector of transistor 30 and the base of transistor 46 and its collector coupled to conductor 44 further buffers the collector of transistor 30 from the effects of load currents sourced at node 66 to a load means connected thereto. Additionally, transistor 52 also ensures that the collector voltage of transistor 30 equals the collector voltage of transistor 28 to prevent mismatch between the two transistors.
  • Resistor 68 is connected between the emitter of transistor 52 and output terminal 66 at which is produced regulated output voltage V out .
  • V out V BE36 (1 + R64/R56 ) + ⁇ V BE R64/R34 (4) where R64 is the value of resistor 64.
  • V out can be set to any desired voltage and any temperature coefficient independently of one another.
  • V OUT is taken at output 66 in the preferred embodiment, a regulated output voltage is also produced at node 62 which could be used as an output voltage of the regulator.
  • a novel voltage regulator comprising a thermal current source for providing a thermal current having an adjustable temperature coefficient and means for developing a voltage proportional to the thermal current and combining the voltage with another voltage of a different temperature coefficient to produce a combined voltage the magnitude and temperature coefficient of which can be independently controlled.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Power Engineering (AREA)
  • Nonlinear Science (AREA)
  • Control Of Electrical Variables (AREA)
  • Amplifiers (AREA)
  • Continuous-Control Power Sources That Use Transistors (AREA)
  • Semiconductor Integrated Circuits (AREA)
EP87111725A 1986-10-06 1987-08-13 Voltage regulator having a precision thermal current source Expired - Lifetime EP0264563B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US915481 1986-10-06
US06/915,481 US4677368A (en) 1986-10-06 1986-10-06 Precision thermal current source
US06/915,483 US4683416A (en) 1986-10-06 1986-10-06 Voltage regulator
US915483 1986-10-06

Publications (2)

Publication Number Publication Date
EP0264563A1 EP0264563A1 (en) 1988-04-27
EP0264563B1 true EP0264563B1 (en) 1993-11-03

Family

ID=27129670

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87111725A Expired - Lifetime EP0264563B1 (en) 1986-10-06 1987-08-13 Voltage regulator having a precision thermal current source

Country Status (4)

Country Link
EP (1) EP0264563B1 (ko)
JP (1) JPH0760352B2 (ko)
KR (1) KR950010131B1 (ko)
DE (1) DE3788033T2 (ko)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5029295A (en) * 1990-07-02 1991-07-02 Motorola, Inc. Bandgap voltage reference using a power supply independent current source
IT1244341B (it) * 1990-12-21 1994-07-08 Sgs Thomson Microelectronics Generatore di tensione di riferimento con deriva termica programmabile
JP2861593B2 (ja) * 1992-01-29 1999-02-24 日本電気株式会社 基準電圧発生回路
AT403532B (de) * 1994-06-24 1998-03-25 Semcotec Handel Verfahren zur temperaturstabilisierung
GB2332760A (en) * 1997-12-24 1999-06-30 Motorola Inc Low voltage stabilised current source
JP5839953B2 (ja) 2011-11-16 2016-01-06 ルネサスエレクトロニクス株式会社 バンドギャップリファレンス回路及び電源回路
CN114815950B (zh) * 2022-05-27 2024-03-12 浙江地芯引力科技有限公司 电流产生电路、芯片及电子设备

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3887863A (en) * 1973-11-28 1975-06-03 Analog Devices Inc Solid-state regulated voltage supply
US4157493A (en) * 1977-09-02 1979-06-05 National Semiconductor Corporation Delta VBE generator circuit
JPS5659321A (en) * 1979-08-09 1981-05-22 Toshiba Corp Constant-current regulated power circuit
US4350904A (en) * 1980-09-22 1982-09-21 Bell Telephone Laboratories, Incorporated Current source with modified temperature coefficient
US4590419A (en) * 1984-11-05 1986-05-20 General Motors Corporation Circuit for generating a temperature-stabilized reference voltage

Also Published As

Publication number Publication date
JPS6398159A (ja) 1988-04-28
JPH0760352B2 (ja) 1995-06-28
EP0264563A1 (en) 1988-04-27
DE3788033D1 (de) 1993-12-09
KR880005501A (ko) 1988-06-29
DE3788033T2 (de) 1994-03-03
KR950010131B1 (ko) 1995-09-07

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