Non-volatile memory with linear hot-electron injection technique and strain gauge using the same

• US 9,331,265 B2
• Filed: 01/28/2013
• Issued: 05/03/2016
• Est. Priority Date: 02/23/2012
• Status: Active Grant

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Chakrabartty, Shantanu
• Primary Examiner(s): Noori, Max
• Application Number:
  US14/380,122
• Publication Number:
  US 20150027237A1
• Time in Patent Office: 1,191 Days
• Field of Search: 738/626.8, 737/80, 737/60, 737/77
• US Class Current: 1/1
• CPC Class Codes: A61B 5/4509 Bone density determination
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/4533 Ligaments
• CPC Class Codes: A61B 5/6847 mounted on an invasive device
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G11C 16/3468 Prevention of overerasure or overprogramming, e.g. by verifying whilst erasing or writing
• CPC Class Codes: G11C 16/3481 Circuits or methods to verify correct programming of nonvolatile memory cells whilst programming is in progress, e.g. by detecting onset or cessation of current flow in cells and using the detector output to terminate programming
• CPC Class Codes: G11C 16/3486 Circuits or methods to prevent overprogramming of nonvolatile memory cells, e.g. by detecting onset or cessation of current flow in cells and using the detector output to terminate programming
• CPC Class Codes: G11C 27/005 with non-volatile charge storage, e.g. on floating gate or MNOS
• CPC Class Codes: H01L 29/7884 charging by hot carrier injection
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 39/00 Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00

Abstract

A linear hot-electron injection technique is provided for a non-volatile memory arrangement. The non-volatile memory is comprised of: a floating gate transistor; a capacitor with a first terminal electrically coupled to the gate node of the floating gate transistor; a current reference circuit electrically coupled to the source node of the floating gate transistor; and a feedback circuit electrically coupled between the source node of the floating gate transistor and a second terminal of the capacitor. The feedback circuit operates to adjust a voltage at the gate node of the floating gate transistor in accordance with a source-to-drain voltage across the floating gate transistor.

Claims

1. A self-powered static-strain sensor, comprising:

a piezoelectric member that generates a voltage in response to as mechanical strain; and

a non-volatile memory circuit powered by the voltage received from the piezoelectric member and includes

a floating gate transistor having a gate node and a source node;

a capacitor having a first terminal and a second terminal, the first terminal electrically coupled to the gate node of the floating gate transistor;

a current reference circuit electrically coupled to the source node of the floating gate transistor and operable to source a current therein; and

a feedback circuit electrically coupled between the source node of the floating gate transistor and the second terminal of the capacitor, and operable to adjust a voltage at the gate node of the floating gate transistor in accordance with a source-to-drain voltage across the floating gate transistor.

2. The self-powered static-strain sensor of claim 1 wherein the current reference circuit operates to hold the source current constant, thereby ensuring that the source-to-gate voltage of the floating gate transistor remains constant.

3. The self-powered static-strain sensor of claim 1 wherein the current reference circuit is implemented by two transistors in a cascading arrangement.

4. The self-powered static-strain sensor of claim 1 wherein the feedback circuit is further defined as an operational amplifier having an inverting terminal electrically coupled to the source node of the floating gate transistor, a non-inverting terminal electrically coupled to a reference voltage and an output electrically coupled to the second terminal of the capacitor.

5. The self-powered static-strain sensor of claim 1 wherein the feedback circuit is further defined as a single-stage, single ended amplifier.

6. The self-powered static-strain sensor of claim 1 wherein the non-volatile memory circuit further comprises a tunnel capacitor electrically coupled to the gate node of the floating gate transistor for removing electrons from the floating gate transistor.

7. The self-powered static-strain sensor of claim 1 wherein the non-volatile memory circuit further comprises:

a switch electrically coupled between the second terminal of the capacitor and ground; and

a controller interfaced with the switch to control operation thereof, such that the switch is opened to inject current into the floating gate transistor and is closed to remove electrons from the floating gate transistor.

8. The self-powered static-strain sensor of claim 1 further comprises a rectifier interposed between the piezoelectric member and the non-volatile memory circuit.

9. A self-powered static-strain sensor, comprising:

a piezoelectric member that generates a voltage in response to as mechanical strain;

a non-volatile memory arrangement having an array of memory circuits powered by voltage received from the piezoelectric member, each memory circuit includes

a floating gate transistor having a gate node and a source node;

a capacitor having a first terminal and a second terminal, the first terminal electrically coupled to the gate node of the floating gate transistor;

a current reference circuit electrically coupled to the source node of the floating gate transistor and operable to source a current therein;

a feedback circuit electrically coupled between the source node of the floating gate transistor and the second terminal of the capacitor, and operable to adjust a voltage at the gate node of the floating gate transistor in accordance with a source-to-drain voltage across the floating gate transistor; and

a switch electrically coupled between the second terminal of the capacitor and ground; and

a controller interfaced with each of the switches in the array of memory circuits to control operation thereof.

10. The self-powered static-strain sensor of claim 9 wherein the current reference circuit in each memory circuit operates to hold the source current constant, thereby ensuring that source-to-gate voltage of the corresponding floating gate transistor remains constant.

11. The self-powered static-strain sensor of claim 9 wherein the current reference circuit is implemented by two transistors in a cascading arrangement.

12. The self-powered static-strain sensor of claim 9 wherein the feedback circuit is further defined as an operational amplifier having an inverting terminal electrically coupled to the source node of the floating gate transistor, a non-inverting terminal electrically coupled to a reference voltage and an output electrically coupled to the second terminal of the capacitor.

13. The self-powered static-strain sensor of claim 9 wherein each memory circuit further comprises a tunnel capacitor electrically coupled to the gate node of the floating gate transistor for removing electrons from the floating gate transistor.

14. A self-powered static-strain sensor, comprising:

a piezoelectric member having a first and second terminal and operable to generate a voltage signal in response to a mechanical strain;

a first rectifier electrically coupled to the first terminal of the piezoelectric member and operable to extract a positive voltage from the voltage signal;

a first non-volatile memory circuit powered by the positive voltage received from the first rectifier, the first non-volatile memory includes

a first floating gate transistor having a gate node and a source node;

a first capacitor having a first terminal and a second terminal, the first terminal electrically coupled to the gate node of the first floating gate transistor;

a first current source electrically coupled to the source node of the first floating gate transistor and operable to source an injection current into the first floating gate transistor; and

a first feedback circuit electrically coupled between the source node of the first floating gate transistor and the second terminal of the first capacitor, and operable to adjust a voltage at the gate node of the floating gate transistor in accordance with a source-to-drain voltage across the first floating gate transistor;

a second rectifier electrically coupled to the second terminal of the piezoelectric member and operable to extract a negative voltage from the voltage signal;

a second non-volatile memory circuit powered by the negative voltage received from the second rectifier, the second non-volatile memory includes

a second floating gate transistor having a gate node and a source node;

a second capacitor having a first terminal and a second terminal, the first terminal electrically coupled to the gate node of the second floating gate transistor;

a second current source electrically coupled to the source node of the second floating gate transistor and operable to source an injection current into the second floating gate transistor; and

a second feedback circuit electrically coupled between the source node of the second floating gate transistor and the second terminal of the first capacitor, and operable to adjust a voltage at the gate node of the second floating gate transistor in accordance with a source-to-drain voltage across the second floating gate transistor.

15. The self-powered static-strain sensor of claim 14 wherein the first current source is configured to receive the positive voltage and generate the injection current for the first floating gate transistor, and the second current source is configured to receive the negative voltage and generate the injection current for the second floating gate transistor.

16. The self-powered static-strain sensor of claim 14 wherein the first and second feedback circuits are further defined as an operational amplifier having an inverting terminal electrically coupled to the source node of the respective floating gate transistor, a non-inverting terminal electrically coupled to a reference voltage and an output electrically coupled to the second terminal of the capacitor.

17. The self-powered static-strain sensor of claim 14 wherein the first and second non-volatile memory circuits further include a tunnel capacitor electrically coupled to the gate node of the respective floating gate transistor for removing electrons from the floating gate transistor.

18. The self-powered static-strain sensor of claim 17 wherein the first and second non-volatile memory circuits further include a switch electrically coupled between the second terminal of the capacitor and ground, such that the switch is closed to remove electrons from the respective floating gate transistor.