Voltage pump with diode for pre-charge

• US 6,483,378 B2
• Filed: 09/21/2001
• Issued: 11/19/2002
• Est. Priority Date: 07/06/2000
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Blodgett, Greg A.
• Primary Examiner(s): Callahan, Timothy P.
• Assistant Examiner(s): Tra, Quan
• Application Number:
  US09/956,812
• Publication Number:
  US 20020008569A1
• Time in Patent Office: 424 Days
• Field of Search: 327/536, 327/537, 327/589
• US Class Current: 327/536
• CPC Class Codes: H02M 3/073 Charge pumps of the Schenkel-type

Abstract

A charge pump system for providing a voltage to a semiconductor device is disclosed. Current charge pumps use a separate pre-charge capacitor and pre-charge circuitry for the boot circuit which provides the gate voltage for the output transistor. The present invention eliminates the need for the separate pre-charge capacitor and pre-charge circuitry by the use of a single diode. The net effect is a more efficient and smaller charge pump circuit.

Claims

1. A charge pump comprising:

a clock generator for supplying at least one clock signal; and

at least one charge pump stage, each pump stage comprising,

a first boot circuit for supplying a charge pump voltage, said first boot circuit having an input for accepting said at least one clock signal and a first output for providing an increased magnitude voltage;

an output transistor coupled between said output of said first boot circuit and an output terminal;

a second boot circuit controlling a gate of said output transistor, said second boot circuit having an input for accepting said at least one clock signal and an second output coupled to the gate of said output transistor,

a pre-charge circuit for supplying a pre-charge voltage to said second boot circuit, said pre-charge circuit consisting essentially of a diode coupled between the output of said first boot circuit and the output of said second boot circuit, to permit current to flow from the output of the first boot circuit to the output of the second boot circuit.

2. The charge pump of claim 1, wherein said pre-charge voltage is supplied to a pump capacitor of said second boot circuit.

3. The charge pump of claim 2, wherein said second boot circuit does not include a pre-charge capacitor.

4. The charge pump of claim 1, wherein said first boot circuit further comprises:

a capacitor for storing a second pre-charge voltage when said at least one clock signal is low; and

a unidirectional current device passing said second pre-charge voltage to said capacitor.

5. The charge pump of claim 1, wherein said diode is coupled between said first output and said second output.

6. The charge pump of claim 1, further comprising at least N of said pump stages having their output terminals connected to a common output terminal, said two pump stages being operated 360/N degree out of phase with respect to each other by said at least one clock signal.

7. The charge pump of claim 6, wherein N equals 2.

8. A processor system comprising:

a processor; and

a memory device coupled to said processor, at least one of said memory device and said processor containing a charge pump system, said charge pump system comprising,

a clock generator for supplying at least one clock signal; and

at least one charge pump stage, each pump stage comprising,

a first boot circuit for supplying a charge pump voltage, said first boot circuit having an input for accepting said at least one clock signal and a first output for providing an increased magnitude voltage;

an output transistor coupled between said output of said first boot circuit and an output terminal;

a second boot circuit controlling a gate of said output transistor, said second boot circuit having an input for accepting said at least one clock signal and an second output coupled to the gate of said output transistor,

a pre-charge circuit for supplying a pre-charge voltage to said second boot circuit, said pre-charge circuit consisting essentially of a diode coupled between the output of said first boot circuit and the output of said second boot circuit, to permit current to flow from the output of the first boot circuit to the output of the second boot circuit.

9. The processor system of claim 8, wherein said pre-charge voltage is supplied to a pump capacitor of said second boot circuit.

10. The processor system of claim 9, wherein said second boot circuit does not include a pre-charge capacitor.

11. The processor system of claim 8, wherein said first boot circuit further comprises:

a capacitor for storing a second pre-charge voltage when said at least one clock signal is low; and

a unidirectional current device passing said second pre-charge voltage to said capacitor.

12. The processor system of claim 8, wherein said diode is coupled between said first output and said second output.

13. The processor system of claim 8, further comprising at least N of said pump stages having their output terminals connected to a common output terminal, said two pump stages being operated 360/N degree out of phase with respect to each other by said at least one clock signal.

14. The processor system of claim 13, wherein N equals 2.

15. An integrated circuit comprising:

a die having a charge pump system fabricated thereon, said charge pump comprising,

a clock generator for supplying at least one clock signal; and

at least one charge pump stage, each pump stage comprising,

a first boot circuit for supplying a charge pump voltage, said first boot circuit having an input for accepting said at least one clock signal and a first output for providing an increased magnitude voltage;

an output transistor coupled between said output of said first boot circuit and an output terminal;

a second boot circuit controlling a gate of said output transistor, said second boot circuit having an input for accepting said at least one clock signal and an second output coupled to the gate of said output transistor,

a pre-charge circuit for supplying a pre-charge voltage to said second boot circuit, said pre-charge circuit consisting essentially of a diode coupled between the output of said first boot circuit and the output of said second boot circuit, to permit current to flow from the output of the first boot circuit to the output of the second boot circuit.

16. The processor system of claim 15, wherein said pre-charge voltage is supplied to a pump capacitor of said second boot circuit.

17. The processor system of claim 16, wherein said second boot circuit does not include a pre-charge capacitor.

18. The processor system of claim 15, wherein said first boot circuit further comprises:

a capacitor for storing a second pre-charge voltage when said at least one clock signal is low; and

a unidirectional current device passing said second pre-charge voltage to said capacitor.

19. The processor system of claim 15, wherein said diode is coupled between said first output and said second output.

20. The processor system of claim 19, further comprising at least N of said pump stages having their output terminals connected to a common output terminal, said two pump stages being operated 360/N degree out of phase with respect to each other by said at least one clock signal.

21. A method of providing a charge pump voltage, said method comprising:

performing at least one voltage boosting process, each of said voltage boosting process comprising;

booting a first voltage to an second voltage greater in magnitude than said first voltage with a first boot circuit in response to a clock signal;

booting a third voltage to a fourth voltage greater in magnitude than said third voltage with a second boot circuit including a pump capacitor, in response to a clock signal;

gating said second voltage from said first boot circuit to an output terminal, wherein said gating is controlled by the second boot circuit; and

pre-charging said pump capacitor by supplying a pre-charge voltage from said first boot circuit to said pump capacitor via a pre-charge circuit, said pre-charge circuit consisting essentially of a diode coupled between the output of said first boot circuit and the output of said second boot circuit, to permit current to flow from the output of the first boot circuit to the output of the second boot circuit.

22. The method of claim 21, further comprising:

supplying said first voltage as a pre-charge voltage to said first boot circuit through a unidirectional current device.