Solid-state regulated voltage supply

• US 3,887,863 A
• Filed: 11/28/1973
• Issued: 06/03/1975
• Est. Priority Date: 11/28/1973
• Status: Expired due to Term

• Current Assignee: Adrian P. Brokaw
• Original Assignee: Adrian P. Brokaw
• Inventors: Brokaw, Adrian Paul
• Primary Examiner(s): Pellinen, A. D.
• Application Number:
  US05/419,616
• Time in Patent Office: 552 Days
• Field of Search: 307/296,297 323/1,4,16,19,22T,23,25
• US Class Current: 323/314
• 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

Abstract

A solid-state (IC) regulated voltage supply compensated for effects of changes in temperature comprising first and second transistors operated at different current densities. Associated circuitry develops a voltage proportional to the Delta VBE of the two transistors and having a positive temperature coefficient. This voltage is connected in series with the VBE voltage of one of the two transistors, having a negative temperature coefficient, to produce a resultant voltage with nearly zero temperature coefficient. A feedback circuit responsive to current flow through the two transistors automatically adjusts the base voltages to maintain a predetermined ratio of current density for the two transistors. Other embodiments provide higher-level DC outputs and compensation for base current flow.

Claims

1. A solid-state temperature-compensated voltage supply comprising:

first and second transistors;

a resistor connected between the emitter of said first transistor and the emitter of said second transistor;

circuit means for furnishing supply voltage to said two transistors to develop current flow therethrough with the current through said first transistor also flowing through said resistor;

means for sensing the magnitudes of the respective currents flowing through said two transistors;

voltage-control means responsive to the currents sensed by said sensing means and operable to adjust the base potentials of said transistors to maintain the magnitudes of said transistor currents at levels which provide a predetermined non-unity ratio of current densities within the two transistors and thereby cause the current through said resistor to vary positively with respect to temperature of said two transistors;

means for developing a first voltage proportional to said resistor current and for combining said first voltage with a second voltage which varies negatively with respect to temperature to produce a combined voltage having minimal overall variation with respect to temperature; and

output means coupled to said last-named means and including an output terminal providing an output voltage proportional to said combined voltage.

2. Apparatus as in claim 1, wherein said voltage-control means comprises a high-gain amplifier serving as a comparator responsive to signals proportional to said transistor currents to produce an output signal corresponding to the difference between said signals proportional to said currents;

and means coupling a voltage proportional to said output signal to the bases of said transistors to drive the base potentials to values providing the desired ratio of current densitiEs in said transistors.

3. Apparatus as in claim 2, including a voltage-dividing network coupled in the output of said amplifier and having a network terminal providing a voltage which is a predetermined fraction of the amplifier output;

and means coupling said network terminal to the bases of said transistors.

4. Apparatus as in claim 2, wherein said sensing means comprises first and second load resistors connected in the collector circuits of said transistors, respectively.

5. Apparatus as in claim 1, wherein said transistor bases are connected together to provide equal base potentials.

6. Apparatus as in claim 1, wherein said transistor bases are coupled together by resistor means to compensate for the effects of change in base current.

7. A solid-state temperature-compensated voltage supply comprising:

first and second transistors;

positive and negative voltage lines;

means coupling one of said voltage lines to the transistor collectors;

a resistor connected in a circuit between the emitter of said first transistor and the other of said voltage lines, to carry the current flowing through said first transistor;

means connecting the emitter of said second transistor to the end of said resistor which is remote from said first transistor emitter;

means for sensing the magnitudes of the respective currents flowing through said first and second transistors;

voltage-control means responsive to said transistor currents and operable to adjust the base potentials of said transistors to maintain the magnitudes of said transistor currents at levels which provide a predetermined non-unity ratio of current densities when the two transistors and thereby cause the current through said resistor to vary positively with respect to temperature of said two transistors;

means for developing a first voltage proportional to said resistor current and for combining said first voltage with a second voltage which varies negatively with respect to temperature to produce a combined voltage having minimal variation with respect to temperture; and

output means coupled to said last-named means and including an output terminal providing an output voltage proportional to said combined voltage.

8. Apparatus as in claim 7, including first and second load resistors in the collector circuits of said transistors, respectively, to develop voltage drops proportional to the transistor currents flowing therethrough;

an amplifier having its input terminals connected to said collector circuits respectively to receive therefrom voltages proportional to the corresponding collector currents; and

means connecting the output of said amplifier to the bases of said transistors to apply thereto a voltage proportional to the amplifier output to drive the base potentials to a value providing a null voltage at the input of said amplifier.

9. Apparatus as in claim 8, including a voltage-divider network connected to the output of said amplifier;

and means coupling an intermediate point of said network to said transistor bases to provide thereto a control voltage which is a predetermined fraction of the amplifier output.

10. A solid-state regulated-voltage supply comprising:

first and second transistors;

positive and negative supply voltage lines;

means coupling one of said supply voltage lines to the collectors of said two transistors;

first and second resistors connected in series between the emitter of said first transistor and the other of said supply voltage lines to carry the current flowing through said first transistor;

means connecting the emitter of said second transistor to the junction between said first and second resistors, whereby said second resistor also carries the current flowing through said second transistor;

means establishing a predetermined relationship between the base potentials of said two transistors;

circuit means for establishing different current densities in said two transistoRs with the ratio of current densities being set at a predetermined value to cause the currents through said resistors to vary positively with respect to temperature; and

output circuit means connected to the base of said second transistor for developing at an output terminal an output voltage proportional to the voltage across said second resistor combined serially with the VBE voltage of said second transistor.

11. In a voltage supply of the type comprising means to produce a first voltage having a positive temperature coefficient for combination with a second voltage having a negative temperature coefficient so as to develop a combined voltage having a substantially reduced overall temperature coefficient;

the improvement in said means for producing said first voltage having a positve temperature coefficient which comprises;

first and second transistors arranged to conduct respective currents therethrough;

means connecting the bases of said two transistors together to provide for tracking of the base potentials;

sensing means coupled to both of said transistors and responsive to said currents passing therethrough;

voltage-control means coupled to said sensing means and having an output circuit for producing a control voltage responsive to the change in the relative levels of said transistor currents;

means connecting said output circuit to the base of a least one of said transistors for automatically adjusting the base voltage thereof responsive to said control voltage so as to maintain the ratio of said transistor currents at a value which provides a non-unity ratio of current densities within said transistors; and

means connected to the emitters of both of said at to produce a voltage proportional to the difference in base-to-emitter voltage of said two transistors to serve as said first voltage having a positive temperature coefficient.

12. A voltage supply as claimed in claim 11, wherein said voltage-control means comprises a high-gain amplifier producing said control voltage at its output.

13. A voltage supply as claimed in claim 12, including means coupling to said one transistor base a voltage proportional to the output voltage of said amplifier.

14. A voltage supply as claimed in claim 13, wherein said coupling means comprises voltage-dividing means to couple to said transistor base a voltage which is a pre-set fraction of the amplifier output voltage.

15. A voltage supply as claimed in claim 11, wherein the emitters of said two transistors have substantially different areas.

16. A voltage supply as claimed in claim 15, wherein said transistor currents are maintained equal.

17. A solid-state temperature-compensated voltage supply comprising:

first and second transistors arranged to conduct respective currents;

voltage means to provide base voltage to said transistor bases to produce current densities therein having a non-unity ratio;

circuit means including resistance means connected to the emitters of said two transistors to develop a first voltage proportional to the difference in base-to-emitter voltages of said transistors and to apply said first voltage to the emitter of said second transistor;

means coupling the bases of said two transistors together to provide for tracking of the base potentials;

an output terminal; and

means coupling said output terminal to the base of said second transistor to provide at said output terminal an output voltage proportional to said first voltage combined with the base-to-emitter voltage of said second transistor.

18. A voltage supply as claimed in claim 17, wherein said voltage means comprises an amplifier the input of which is coupled to said two transistors to receive signals therefrom corresponding to the transistor currents;

and means coupling the output of said amplifier to the bases of said two transistors to automatically maintain the base potentials at the value which produces the required transistor cuRrents to maintain the transistor current densities at the desired non-unity ratio.