Method and device to speed-up leakage based PUF generators under extreme operation conditions

Patent metadata

Field	Value
Publication number	US-10164640-B1
Application number	US-201816004209-A
Country	US
Kind code	B1
Filing date	Jun 8, 2018
Priority date	Jun 8, 2018
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

Disclosed is a physical unclonable function generator circuit and method. In one embodiment, a physical unclonable function (PUF) generator includes: a PUF cell array comprising a plurality of bit cells, wherein each of the plurality of bit cells comprises at least two inverters, at least one floating capacitor, at least two dynamic nodes, wherein the at least one floating capacitor is coupled between a first inverter at a first dynamic node and a second inverter at a second dynamic node; a PUF controller coupled to the PUF cell array, wherein the PUF controller is configured to charge the first dynamic nodes through the respective first inverters in the plurality of bit cells; and a finite state machine coupled to the PUF cell array configured to determine voltage levels on the second dynamic nodes through the respective second inverters in the plurality of bit cells to determine first logical states of the plurality of bit cells at at least one sampling time and generate a PUF signature.

First claim

What is claimed is:

1. A physical unclonable function (PUF) generator comprising:
a PUF cell array comprising a plurality of bit cells, wherein each of the plurality of bit cells comprises at least two inverters, at least one floating capacitor, and at least two dynamic nodes, wherein the at least one floating capacitor is coupled between a first inverter at a first dynamic node and a second inverter at a second dynamic node;
a PUF controller coupled to the PUF cell array, wherein the PUF controller is configured to charge the first dynamic nodes through the respective first inverters in the plurality of bit cells; and
a finite state machine coupled to the PUF cell array configured to determine voltage levels on the second dynamic nodes through the respective second inverters in the plurality of bit cells to determine first logical states of the plurality of bit cells at at least one sampling time and generate a PUF signature.

2. The PUF generator of claim 1 , wherein the at least two inverters each comprises a first NMOS transistor and a first PMOS transistor.

3. The PUF generator of claim 1 , wherein the at least one floating capacitor comprises a second NMOS transistor, wherein a gate terminal of the second NMOS transistor is coupled to the first dynamic node and drain, source and body terminals are coupled together to the second dynamic node.

4. The PUF generator of claim 1 , wherein the floating capacitor further comprises a first channel dimension, wherein the first channel dimension is greater than second channel dimensions of the first NMOS and the first PMOS transistors in the at least two inverters, wherein the channel dimension comprises at least one of the following: a channel width and a channel length.

5. The PUF generator of claim 3 , wherein the second NMOS transistor is manufactured in a first P-well, wherein the first P-well is manufactured in a first N-well in a p-type substrate.

6. The PUF generator of claim 2 , wherein the first PMOS transistor in the at least two inverters of each of the plurality of bit cells is manufactured in a second N-well and the first NMOS transistor in the at least two inverters of each of the plurality of bit cells is manufactured directly in the p-type substrate.

7. The PUF generator of claim 1 , wherein the finite state machine further comprises:
a plurality of dynamic flip-flop (DFF) circuits wherein each of the plurality of DFF circuits is coupled to each of the plurality of bit cells respectively, wherein the plurality of DFF circuits is configured to determine the first logical states of the plurality of bit cells;
a population count circuit coupled to the plurality of DFF circuits, wherein the population count circuit is configured to determine a first number of bit cells with logic states of 0 and a second number of bit cells with logic states of 1 at each of the at least one sampling time; and
an evaluation logic circuit coupled between the population count circuit and the plurality of DFF circuits, wherein the evaluation logic circuit is configured to compare the first and second number of bit cells at each of the at least one sampling time to determine the PUF signature.

8. The PUF generator of claim 1 , wherein the PUF signature comprises N bits of logic 0's and M bits of logic 1's, wherein M is not less than N.

9. A method to configure a physical unclonable function (PUF) generator for generating a PUF signature, the method comprising:
pre-charging a first dynamic node to a first voltage through a first inverter in each of a plurality of bit cells in a PUF cell array;
charging a second dynamic node through at least one floating capacitor in each of the plurality of bit cells in the PUF cell array;
determining a voltage level on the second dynamic node through a second inverter in each of the plurality of bit cells in the PUF cell array at at least one sampling time; and
generating a PUF signature.

10. The method of claim 9 , wherein the first and second inverters each comprises a first NMOS transistor and a first PMOS transistor.

11. The method of claim 9 , wherein the at least one floating capacitor comprises a second NMOS transistor, wherein a gate terminal of the second NMOS transistor is coupled to the first dynamic node and drain, source and body terminals are coupled together to the second dynamic node.

12. The method of claim 9 , wherein the second NMOS transistor is manufactured in a first P-well, wherein the first P-well is manufactured in a first N-well in a p-type substrate.

13. The method of claim 10 , wherein the first PMOS transistor in the at least two inverters of each of the plurality of bit cells is manufactured in a second N-well and the first NMOS transistor in the first and second inverters of each of the plurality of bit cells is manufactured directly in the p-type substrate.

14. The method of claim 9 , wherein the determining further comprising:
determining the first logical states of the plurality of bit cells using a plurality of DFF circuits; and
determining a first number of bit cells with logic states of 0 and a second number of bit cells with logic states of 1 at each of the at least one sampling time using a population counter circuit.

15. The method of claim 14 , wherein the plurality of DFF circuits is coupled to the plurality of bit cells, respectively.

16. The method of claim 9 , wherein the PUF signature comprises N bits of logic 0's and M bits of logic 1's, wherein M is not less than N.

17. A physical unclonable function (PUF) generator for generating a PUF signature, the PUF generator comprising:
a PUF cell array comprising a plurality of bit cells, wherein each of the plurality of bit cells comprises at least two inverters, at least one floating capacitor, at least two dynamic nodes, wherein the at least one floating capacitor is coupled between a first inverter at a first dynamic node and a second inverter at a second dynamic node;
a PUF controller coupled to the PUF cell array, wherein the PUF controller is configured to charge the first dynamic nodes through the respective first inverters in the plurality of bit cells;
a plurality of dynamic flip-flop (DFF) circuits, wherein the plurality of DFF circuits is coupled to the plurality of bit cells respectively, wherein the plurality of DFF circuits is configured to determine a first logical states of the plurality of bit cells;
a population count circuit coupled to the plurality of DFF circuits, wherein the population count circuit is configured to determine a first number of bit cells with logic states of 0 and a second number of bit cells with logic states of 1 in the plurality of bit cells at each of the at least one sampling time; and
an evaluation logic circuit coupled between the population count circuit and the plurality of DFF circuits, wherein the evaluation logic circuit is configured to compare the first and second number of bit cells at each of the at least one sampling time to determine the PUF signature.

18. The PUF generator of claim 17 , wherein the at least two inverters each comprises a first NMOS transistor and a first PMOS transistor.

19. The PUF generator of claim 17 , wherein the at least one floating capacitor comprises a second NMOS transistor, wherein a gate terminal of the second NMOS transistor is coupled to the first dynamic node and drain, source and body terminals are coupled together to the second dynamic node.

20. The PUF generator of claim 17 , wherein the floating capacitor further comprises a first channel dimension, wherein

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Lu Shih-Lien Linus
• Lee Cheng-En
• Tsai Jui-Che

Classifications

• H03K19/17768 Primary

  for security · CPC title

• G11C16/22

  Safety or protection circuits preventing unauthorised or accidental access to memory cells · CPC title

• G06F21/73

  by creating or determining hardware identification, e.g. serial numbers · CPC title

• G06F12/1408

  by using cryptography (for digital transmission H04L9/00) · CPC title

• H04L9/3278

  using physically unclonable functions [PUF] · CPC title