Feedback-controlled body-bias voltage source

• US 7,649,402 B1
• Filed: 12/23/2003
• Issued: 01/19/2010
• Est. Priority Date: 12/23/2003
• Status: Active Grant

• 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): Donovan; Lincoln
• Assistant Examiner(s): Hiltunen; Thomas J
• Application Number:
  US10/747,016
• Time in Patent Office: 2,219 Days
• Field of Search: 327/534, 327/535, 327/536, 327/537, 363/59
• US Class Current: 327/536
• CPC Class Codes: G05F 1/46 wherein the variable actually regulated by the final control device is dc G05F1/625 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 3/078 with means for reducing the back bias effect, i.e. the effect which causes the threshold voltage of transistors to increase as more stages are added to the converters

Abstract

A body-bias voltage source having an output monitor, charge pump, and shunt. A shunt circuit having on/off control is coupled to the output monitor and to the output of the charge pump. Upon sensing that the output voltage of the charge pump is above a desired value, the output monitor may disable the charge pump circuit and may enable the shunt circuit to reduce the voltage at the output of the charge pump. When the voltage output of the charge pump is below the desired value, the output monitor may disable the shunt circuit and may enable the charge pump circuit. A shunt circuit having proportional control may be substituted for the shunt circuit with on/off control.

Claims

1. A feedback-controlled body-bias voltage source for an integrated circuit comprising:

an output monitor comprising an input for a reference voltage and a sense input for sensing an output voltage, said output monitor for comparing said reference voltage to said output voltage and operable for generating a proportional signal for correcting said output voltage based on said comparing;

a charge pump for generating said output voltage and comprising an enable input coupled to a control output of said output monitor, and a voltage output coupled to said sense input of said output monitor; and

a shunt circuit for correcting said output voltage of said voltage output, said shunt circuit coupled to said voltage output and to said control output of said output monitor, wherein said shunt circuit is configured to be controlled according to said proportional signal of said output monitor, wherein an effective resistance of said shunt circuit is changed in proportion to said proportional signal;

wherein said output monitor is operable to compare said reference voltage to said output voltage while said shunt circuit is activated, wherein said proportional signal has a state between an on state and an off state, wherein said state between said on and off states is proportional to a difference between said output voltage and said reference voltage.

2. The body-bias voltage source of claim 1, wherein said charge pump is configured to be run continuously.

3. The body-bias voltage source of claim 1, further comprising a P-type well coupled to said charge pump.

4. The body-bias voltage source of claim 1, further comprising an N-type well coupled to said charge pump.

5. The body-bias voltage source of claim 1, wherein for an overvoltage condition, said shunt circuit is enabled to provide a discharge path;

and wherein for an undervoltage condition, said shunt circuit is cycled between enabled and disabled if said charge pump is running.

6. An integrated circuit comprising:

a substrate;

a complementary well disposed in said substrate;

a charge pump disposed in said substrate and comprising an output coupled to said complementary well, said charge pump for generating an output voltage;

an output monitor disposed in said substrate and comprising an input for a reference voltage and coupled to said charge pump for sensing said output voltage, said output monitor for comparing said reference voltage to said output voltage; and

a shunt circuit coupled to said charge pump and to said output monitor, wherein enabling said shunt circuit is controlled by said output monitor, wherein for an overvoltage condition, said shunt circuit is enabled to provide a discharge path, and wherein said shunt circuit is configured for proportional control instead of on/off control;

wherein said output monitor is operable to compare said reference voltage to said output voltage while said shunt circuit is activated, wherein said proportional control utilizes a signal that has a state between an on state and an off state, wherein said state between said on and off states is proportional to a difference between said output voltage and said reference voltage.

7. The integrated circuit of claim 6, wherein said substrate is a P-type substrate.

8. The integrated circuit of claim 6, wherein said substrate is an N-type substrate.

9. The integrated circuit of claim 6, wherein said integrated circuit is a mixed-signal integrated circuit.

10. The integrated circuit of claim 6, wherein for an undervoltage condition, said shunt circuit is cycled between enabled and disabled if said charge pump is running.

11. A body-bias voltage source for an integrated circuit comprising:

a charge pump for charging a capacitance associated with a p-n junction and for generating an output voltage;

a servo loop coupling an output of said charge pump to an input of said charge pump, said servo loop comprising a comparator for comparing a reference voltage to said output voltage and operable for generating a proportional signal for correcting said output voltage based on said comparing; and

a shunt circuit coupled to said servo loop and to said charge pump for reducing a voltage across said capacitance, wherein said shunt circuit is configured to be controlled according to said proportional signal of said servo loop, wherein an effective resistance of said shunt circuit is changed in proportion to said proportional signal;

wherein said comparator is operable to compare said reference voltage to said output voltage while said shunt circuit is activated, wherein said proportional signal has a state between an on state and an off state, wherein said state between said on and off states is proportional to a difference between said output voltage and said reference voltage.

12. The body-bias voltage source of claim 11, wherein said servo loop comprises a comparator.

13. The body-bias voltage source of claim 11, wherein said capacitance is associated with an n-well.

14. The body-bias voltage source of claim 11, wherein said capacitance is associated with a p-well.

15. The body-bias voltage source of claim 11, wherein for an overvoltage condition, said shunt circuit is enabled to provide a discharge path;

and wherein for an undervoltage condition, said shunt circuit is cycled between enabled and disabled if said charge pump is running.