Servo loop for well bias voltage source

• US 7,847,619 B1
• Filed: 04/22/2008
• Issued: 12/07/2010
• Est. Priority Date: 12/23/2003
• Status: Expired due to Fees

• Current Assignee: Intellectual Ventures Funding LLC (Intellectual Ventures LLC)
• Original Assignee: Intellectual Ventures Funding LLC (Intellectual Ventures LLC)
• Inventors: Chen, Tien-Min
• Primary Examiner(s): ZWEIZIG, JEFFERY SHAWN
• Application Number:
  US12/107,733
• Time in Patent Office: 959 Days
• Field of Search: 327/534, 327/535, 327/536, 327/537
• US Class Current: 327/536
• CPC Class Codes: G11C 5/145 Applications of charge pumps; Boosted voltage circuits; Clamp circuits therefor G11C5/141 takes precedence
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/071 adapted to generate a negative voltage output from a positive voltage source

Abstract

A servo loop for a charge pump including comparator. A variable resistor and comparator are in series and couple the output of the charge pump to an enable input. A current source/sink coupled to the variable resistor provide a first input voltage to the comparator, with the second input of the comparator being coupled to ground or V_dd. A shunt circuit in parallel with the load at the output of the charge pump is also coupled to the output of the comparator. The charge pump and shunt are alternately enabled and disabled by the comparator to maintain a body-bias supply voltage. The servo loop may be configured to provide body-bias for NFETs or PFETs.

Claims

1. A circuit comprising:

a charge provider circuit operable to receive a control signal and operable to provide a charge to a body-bias voltage source of an integrated circuit responsive to said control signal;

an output monitoring circuit operable to determine, independently of said control signal, whether a voltage at an output node of said charge provider circuit is an over-voltage or an under-voltage that is outside of an acceptable threshold value, wherein said output monitoring circuit is operable, independently of an external signal, to outputs said control signal which is operable to adjust said output node responsive to said determination; and

a shunt circuit operable to provide a discharge path responsive to said control signal based on whether said voltage at said output node exceeds said acceptable threshold value,

wherein said control signal causes said charge provider circuit to provide said charge to said body-bias voltage source based on whether said voltage at said output node is outside of said acceptable threshold value.

2. The circuit of claim 1, wherein said charge provider circuit is a charge pump, and wherein said charge pump is coupled to a substrate.

3. The circuit of claim 1, wherein said shunt circuit comprises an enable input delay.

4. The circuit of claim 1, wherein said output monitoring circuit comprises a comparator.

5. The circuit of claim 1, wherein said output monitoring circuit comprises both NFETs and PFETs in an input stage.

6. The circuit of claim 1, wherein said output of said output monitoring circuit is coupled to said charge provider circuit.

7. A voltage source comprising:

a negative charge provider circuit operable to receive a control signal and operable to provide a negative charge to a body-bias voltage source for an integrated circuit responsive to said control signal;

a comparator operable to determine, independently of said control signal, whether a first voltage at a first input is greater than a reference voltage at a second input, wherein said first voltage is dependent on an output voltage at an output node of said negative charge provider circuit, wherein said comparator is operable, independently of an external signal, to output said control signal in response to said determination, and wherein a voltage of said body-bias voltage source is increased or decreased responsive to said control signal; and

a shunt circuit coupled to an output of said comparator.

8. The voltage source of claim 7, wherein said negative charge provider circuit comprises a negative charge pump, and further comprising:

a current source coupled to said first input; and

a variable resistor coupled between said current source and said negative charge pump, and

wherein said negative charge pump is coupled to a substrate.

9. The voltage source of claim 7, wherein said shunt circuit is also coupled to said negative charge provider circuit, and wherein said shunt circuit is operable to control said output voltage of said negative charge provider circuit responsive to said control signal.

10. The voltage source of claim 9, wherein said shunt circuit is disabled if said negative charge provider circuit is enabled.

11. The voltage source of claim 9, wherein said shunt circuit is operable to reduces said output voltage of said negative charge provider circuit.

12. The voltage source of claim 9, wherein said shunt circuit is operable to provides increased response time of said output voltage.

13. The voltage source of claim 9, wherein said shunt circuit is enabled if said negative charge provider circuit is disabled.

14. The voltage source of claim 9, wherein said shunt circuit comprises a delay at an enable input.

15. The voltage source of claim 7, wherein said output node of said negative charge provider circuit is coupled to a load comprising a reverse-biased p-n junction.

16. A voltage source comprising:

a positive charge provider circuit operable to receive a control signal and operable to provide a positive charge to a body-bias voltage source for an integrated circuit responsive to said control signal;

a comparator operable to determine, independently of said control signal, whether a voltage of an input signal is lower than a reference voltage, wherein said voltage of said input signal is dependent on an output voltage at an output node of said positive charge provider circuit, wherein said comparator is operable, independently of an external signal, to outputs said control signal in response to said determination, and wherein a voltage of said body-bias voltage source is increased or decreased responsive to said control signal; and

a shunt circuit coupled to an output of said comparator.

17. The voltage source of claim 16, wherein said positive charge provider circuit comprises a positive charge pump, and further comprising:

a current sink; and

a variable resistor coupled to said current sink, wherein said variable resistor and said current sink are operable to control an output voltage of said positive charge pump, and

wherein said positive charge pump is coupled to a substrate.

18. The voltage source of claim 16, wherein said shunt circuit is also coupled to said positive charge provider circuit, and wherein said shunt circuit is operable to control said output voltage of said positive charge provider circuit responsive to said control signal.

19. The voltage source of claim 18, wherein said shunt circuit is disabled if said positive charge provider circuit is enabled.

20. The voltage source of claim 18, wherein said shunt circuit is operable to reduces said output voltage of said positive charge provider circuit.

21. The voltage source of claim 18, wherein said shunt circuit is operable to provides increased response time of said output voltage.

22. The voltage source of claim 18, wherein said shunt circuit is enabled if said positive charge provider circuit is disabled.

23. The voltage source of claim 18, wherein said shunt circuit comprises a delay at an enable input.

24. The voltage source of claim 16, wherein said comparator comprises both NFETs and PFETs in an input stage.

25. The voltage source of claim 16, wherein said output node of said positive charge provider circuit is coupled to a load comprising a reverse-biased p-n junction.

26. A circuit comprising:

means for providing a charge to a body-bias voltage source of an integrated circuit responsive to a control signal, wherein said means for providing receives said control signal;

means for determining, independently of said control signal, whether a voltage at an output node of said means for providing said charge is an over-voltage or an under-voltage that is outside of an acceptable threshold value, wherein said means for determining, independently of an external signal, outputs said control signal which is operable to adjust said output node responsive to said determination, and wherein said control signal causes said means for providing said charge to provide said charge to said body-bias voltage source based on whether said voltage at said output node is outside of said acceptable threshold value; and

means for providing a discharge path responsive to said control signal based on whether said voltage at said output node exceeds said acceptable threshold value.

27. The circuit of claim 26, wherein said means for providing said charge is a charge pump, and wherein said charge pump is coupled to a substrate.

28. The circuit of claim 26, wherein said means for providing said discharge path comprises an enable input delay.

29. The circuit of claim 26, wherein said means for determining comprises means for comparing.

30. The circuit of claim 26, wherein said means for determining comprises both NFETs and PFETs in an input stage.

31. The circuit of claim 26, wherein an output of said means for determining is coupled to said means for providing said charge.