Ultra Low Power Oscillator

• US 20100176892A1
• Filed: 01/15/2009
• Published: 07/15/2010
• Est. Priority Date: 01/15/2009
• Status: Abandoned Application

• Current Assignee: Synaptics Incorporated
• Original Assignee: Validity Sensors Incorporated (Synaptics Incorporated)
• Inventors: Erhard, Richard Alexander, Dean, Gregory Lewis, Jandu, Jaswinder, Thompson, Erik Jonathon
• Application Number:
  US12/354,699
• Publication Number:
  US 20100176892A1
• Time in Patent Office: Days
• US Class Current: 331/111
• CPC Class Codes: H03K 4/502 the capacitor being charged from a constant-current source

Abstract

A low power oscillator is disclosed in one embodiment of the invention as including a Schmitt trigger having an input, an output, and an input stage coupled to the input. The input stage may include multiple transistors connected in series between a power source and ground. A switch, controlled by the output of the Schmitt trigger, may be connected in series with the multiple transistors. The switch is configured to interrupt shoot-through current passing through the transistors when the transistors are turned on at the same time. In certain embodiments, the switch may reduce the shoot-through current by substantially half.

Claims

1. A low power oscillator comprising:

a Schmitt trigger comprising an input, an output, and an input stage coupled to the input, the input stage comprising a plurality of field-effect transistors (FETs) connected in series between a power source and a ground; and

a switch controlled by the output of the Schmitt trigger and connected in series with the plurality of FETs, the switch configured to interrupt shoot-through current passing through the plurality of FETs when the FETs are simultaneously turned on.

2. The low power oscillator of claim 1, further comprising a current source connected in series with the plurality of FETs and configured to limit the magnitude of the shoot-through current.

3. The low power oscillator of claim 1, wherein the plurality of FETs comprises at least one n-channel FET and at least one p-channel FET.

4. The low power oscillator of claim 3, wherein the at least one n-channel FET includes at least one NMOS FET, and the at least one p-channel FET includes at least one PMOS FET.

5. The low power oscillator of claim 1, wherein the operation of the switch reduces the shoot-through current by substantially half.

6. The low power oscillator of claim 1, wherein the switch includes at least one FET.

7. The low power oscillator of claim 1, wherein the switch includes at least one of a PMOS FET and an NMOS FET.

8. The low power oscillator of claim 2, wherein the current source includes at least one FET.

9. The low power oscillator of claim 2, wherein the current source includes at least one of a PMOS FET and an NMOS FET.

10. The low power oscillator of claim 1, wherein the input stage is configured to change a state of the output when a voltage of the input reaches one of a lower threshold voltage and an upper threshold voltage.

11. A method for reducing the power consumed by an oscillator, the method comprising:

providing a Schmitt trigger comprising an input, an output, and an input stage coupled to the input, the input stage comprising a plurality of field-effect transistors (FETs) connected in series between a power source and a ground; and

interrupting, in response to feedback from the output, shoot-through current passing through the plurality of FETs when the FETs are simultaneously turned on.

12. The method of claim 11, further comprising limiting the magnitude of the shoot-through current using a current source.

13. The method of claim 11, wherein the plurality of FETs comprises at least one n-channel FET and at least one p-channel FET.

14. The method of claim 13, wherein the at least one n-channel FET includes at least one NMOS FET, and the at least one p-channel FET includes at least one PMOS FET.

15. The method of claim 11, wherein interrupting the shoot-through current comprises reducing the shoot-through current by substantially half.

16. The method of claim 11, wherein interrupting the shoot-through current comprises using a switch to interrupt the shoot-through current.

17. The method of claim 16, wherein the switch includes at least one FET.

18. The method of claim 12, wherein the current source includes at least one FET.

19. The method of claim 11, wherein the input stage is configured to change a state of the output when a voltage of the input reaches one of a lower threshold voltage and an upper threshold voltage.

20. A low power oscillator comprising:

a Schmitt trigger comprising an input, an output, and an input stage coupled to the input, the input stage comprising a plurality of field-effect transistors (FETs) connected in series between a power source and a ground;

a switch controlled by the output of the Schmitt trigger and connected in series with the plurality of FETs, the switch configured to substantially reduce by half the shoot-through current passing through the plurality of FETs when the FETs are simultaneously turned on; and

a current source connected in series with the plurality of FETs and configured to limit the magnitude of the shoot-through current.