Circuit for generating a temperature stabilized output signal

• US 4,380,728 A
• Filed: 05/19/1981
• Issued: 04/19/1983
• Est. Priority Date: 05/19/1981
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Kearney, Mark B.
• Primary Examiner(s): Beha, Jr., William H.
• Application Number:
  US06/265,205
• Time in Patent Office: 700 Days
• Field of Search: 323/269, 323/273280, 323/281, 323/312-314, 323/907, 323/268, 361/152, 361/154
• US Class Current: 323/281
• CPC Class Codes: F02D 2041/2058 using information of the actual current value
• CPC Class Codes: F02D 2041/2065 the control being related to the coil temperature
• CPC Class Codes: F02D 2041/2075 Type of transistors or particular use thereof
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: G05F 3/30 Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities G05F3/26 takes precedence
• CPC Class Codes: Y10S 323/907 Temperature compensation of semiconductor

Abstract

A temperature stabilized voltage reference is generated based on the difference in the base to emitter voltages of a pair of transistors operating at different current densities which is summed with a voltage that is a predetermined fraction of one of the base emitter voltages. This voltage is utilized to provide for a constant current through a load by adjusting the current through a sense resistor to the value of the temperature stabilized voltage.

Claims

1. A circuit for providing a voltage that is substantially independent of temperature variations, comprising in combination:

first and second transistors;

a first resistor coupled between the bases of the first and second transistors;

a second resistor coupled between the base and emitter of the first transistor;

a load impedance coupled between the emitters of the first and second transistors; and

supply means effective to bias the first and second transistors conductive so that the emitter current density of the first transistor is greater than the emitter current density of the second transistor to produce a difference in the base-emitter voltages of the first and second transistors having a positive temperature coefficient, the voltage across the first resistor being proportional to the base-emitter voltage of the first transistor and having a negative temperature coefficient, whereby a substantially temperature independent voltage is provided across the load impedance that is the sum of the voltage across the first resistor having a negative temperature coefficient and the difference in the base to emitter voltages of the first and second transistors having a positive temperature coefficient.

2. A monolithic integrated circuit for producing a voltage V_R that is substantially independent of temperature variations, comprising in combination:

first and second bipolar junction transistors having emitter areas A₁ and A₂, respectively;

a first resistor having a resistance R₁ coupled between the bases of the first and second transistors;

a second resistor having a resistance R₂ coupled between the base and emitter of the first transistor, the ratio R₁ /R₂ being equal to V_R /V_go, where V_go is the semiconductor energy band gap voltage extrapolated to absolute zero;

a load impedance coupled between the emitters of the first and second transistors; and

supply means effective to bias the first and second transistors conductive to supply emitter currents I₁ and I₂, respectively, the product of the ratios I₁ /I₂ and A₂ A₁ being equal to exp[V_R (1-V_be1 /V_go)/(kT/q)] where V_be1 is the base to emitter voltage of the first transistor, k is Boltzmann'"'"'s constant, T is the absolute temperature and q is the charge of an electron, whereby the voltage V_R is produced across the load impedance and is substantially temperature independent.

3. A monolithic integrated circuit for producing a regulated output voltage V_R across a load, comprising:

first and second matched bipolar junction transistors having emitter areas A₁ and A₂, respectively;

means connected in relation to the first and second transistors for operating such transistors so that they provide base-emitter junction voltage drops V_be1 and V_be2 and have emitter currents I_e1 and I_e2, respectively;

first and second resistors having resistance values R₁ and R₂, respectively;

means for connecting the first resistor in relation to the first transistor so as to develop across such first resistor a voltage drop of substantially V_be1 ;

means for connecting the second resistor in relation to the first resistor so as to develop across such second resistor a voltage drop of substantially V_be1 (R₂ /R₁);

means for connecting the first and second resistors and the second transistor in a loop circuit with the load such that the output voltage V_R is substantially equal to V_be1 (R₂ /R₁)+(V_be1 -V_be2), the resistances R₁ and R₂ being such as to substantially satisfy the relation R₂ /R₁ =V_R /V_go and the emitter currents I_e1 and I_e2 and the emitter areas A₁ and A₂ such as to substantially satisfy the relation (I_e1 /I_e2)(A₂ /A₁)=exp[V_R (1-V_be1 /V_go)/(kT/q)] where V_go is the semiconductor band gap voltage extrapolated to absolute zero, k is Boltzmann'"'"'s constant, T is the absolute temperature and q is the charge of an electron, whereby the output voltage V_R is substantially equal to V_go (R₂ /R₁) and is substantially independent of variations in temperature.

4. A monolithic integrated circuit for producing a constant predetermined load current I_L in a load impedance, comprising in combination:

a voltage source coupled with the load impedance effective to supply current therethrough;

a sense resistor having a resistance R_S series coupled with the load impedance, the voltage across the sense resistor having a value V_S when the current through the load impedance is equal to the predetermined value I_L ;

means effective to establish a reference voltage equal to the value V_S, said means including

first and second bipolar transistor having emitter areas A₁ and A₂, respectively,

a first resistor having a resistance R₁ coupled between the bases of the first and second transistors,

a second resistor having a resistance R₂ coupled between the base and emitter of the first transistor, the ratio R₁ /R₂ being equal to V_S /V_go, where V_go is the semiconductor energy band gap voltage extrapolated to absolute zero,

means effective to couple the emitter of the first transistor to the low voltage side of the sense resistor,

means effective to couple the emitter of the second transistor to the high voltage side of the sense resistor, and

supply means effective to bias the first and second transistors conductive to supply emitter currents I₁ and I₂, respectively, the product of the ratios I₁ /I₂ and A₂ /A₁ being equal to exp[V_S (1-V_be1 /V_go)/(kT/q)] where V_be1 is the base-to-emitter voltage of the first transistor, k is Boltzmann'"'"'s constant, T is the absolute temperature and q is the charge of an electron, the sum of the voltages across the first and second resistors and the base-emitter junction voltage of the second transistor providing a temperature stabilized reference voltage equal to V_S ; and

amplifier means coupled with the collector of the second transistor effective to adjust the current through the load impedance when the voltage across the sense resistor deviates from the reference voltage in a sense tending to restore the voltage across the sense resistor to the reference voltage, whereby the current through the load impedance is maintained substantially at the value I_L independent of temperature variations.

5. A monolithic integrated circuit for producing a constant predetermined load current I_L in a load impedance, comprising in combination:

a voltage source coupled with the load impedance effective to supply current therethrough;

a sense resistor having a resistance R_S series coupled with the load impedance, the voltage across the sense resistor having a value V_S when the current through the load impedance is equal to the predetermined value I_L ;

means effective to establish a reference voltage equal to the value V_S, said means including

first and second matched bipolar junction transistors having emitter areas A₁ and A₂, respectively,

means effective to couple the emitter of the first transistor to the low voltage side of the sense resistor,

means effective to couple the emitter of the second transistor to the high voltage side of the sense resistor,

means connected in relation to the first and second transistors for operating such transistors so that they provide base-emitter junction voltage drops V_be1 and V_be2 and have emitter currents I_e1 and I_e2, respectively,

first and second resistors having resistance values R₁ and R₂, respectively,

means for connecting the first resistor in relation to the first transistor so as to develop across such first resistor a voltage drop of substantially V_be1,

means for connecting the second resistor in relation to the first resistor so as to develop across such second resistor a voltage drop of substantially V_be1 (R₂ /R₁), and

means for connecting the first and second resistors and the second transistor in a circuit such that the voltage between the emitters of the first and second transistors is substantially equal to V_be1 (R₂ /R₁)+(V_be1 -V_be2), the resistances R₁ and R₂ being such as to substantially satisfy the relation R₂ /R₁ =V_S /V_go and the emitter currents I_e1 and I_e2 and the emitter areas A₁ and A₂ being such as to substantially satisfy the relation (I_e1 /I_e2)(A₂ /A₁)=exp[V_S (1-V_be1 /V_go)/(kT/q)] where V_go is the semiconductor band gap voltage extrapolated to absolute zero, k is Boltzmann'"'"'s constant, T is the absolute temperature and q is the charge of an electron, the voltage between the emitters of the first and second transistors comprising the reference voltage having the value V_S ; and

amplifier means coupled with the collector of the second transistor effective to adjust the current through the load impedance when the voltage across the sense resistor deviates from the reference voltage in a sense tending to restore the voltage across the sense resistor to the reference voltage, whereby the current through the load impedance is maintained substantially at the value I_L independent of temperature variations.