Static random access memory (SRAM) array power supply circuit

• US 10,607,662 B2
• Filed: 07/27/2018
• Issued: 03/31/2020
• Est. Priority Date: 07/27/2017
• Status: Active Grant

• Current Assignee: Semiconductor Manufacturing International (Beijing) Corporation (Semiconductor Manufacturing International Corporation), Semiconductor Manufacturing International (Shanghai) Corporation (Semiconductor Manufacturing International Corporation)
• Original Assignee: Semiconductor Manufacturing International (Shanghai) Corporation (Semiconductor Manufacturing International Corporation)
• Inventors: Huang, Chen-Yi, Yang, Chia Chi, Luo, Dong Xiang, Huang, Cheng-Tai
• Primary Examiner(s): King, Douglas
• Application Number:
  US16/047,468
• Publication Number:
  US 20190035435A1
• Time in Patent Office: 613 Days
• Field of Search: None
• CPC Class Codes: G11C 11/412 using field-effect transistors only
• CPC Class Codes: G11C 11/419 Read-write [R-W] circuits
• CPC Class Codes: G11C 29/021 in voltage or current generators
• CPC Class Codes: G11C 29/50 Marginal testing, e.g. race, voltage or current testing
• CPC Class Codes: G11C 5/143 Detection of memory cassette insertion or removal; Continuity checks of supply or ground lines; Detection of supply variations, interruptions or levels G11C5/148 takes precedence; Switching between alternative supplies G11C5/141 takes precedence
• CPC Class Codes: G11C 5/147 Voltage reference generators, voltage or current regulators; Internally lowered supply levels; Compensation for voltage drops G11C5/141 takes precedence
• CPC Class Codes: G11C 7/04 with means for avoiding disturbances due to temperature effects
• CPC Class Codes: G11C 7/227 Timing of memory operations based on dummy memory elements or replica circuits

Abstract

A Static Random Access Memory (SRAM) array power supply circuit is presented. The circuit comprises an SRAM test unit having a substantially same structure as a basic SRAM unit in the SRAM array; a switch device connected to a power source, the SRAM test unit, and the SRAM array; and a switch control circuit connected to the SRAM test unit and the switch device. When a test voltage in the SRAM test unit is lower than a threshold voltage, the switch device is closed so that the power source begins to charge the SRAM array and the SRAM test unit. The SRAM test unit provides an early warning for the SRAM array, allowing the latter to be charged upon fulfillment of a condition (e.g., charge is low). Compared to conventional circuits, this circuit provides an output voltage that is more stable and less susceptible to the changes in external conditions such as temperature or pressure.

Claims

1. A power supply circuit for a Static Random Access Memory (SRAM) array, the power supply circuit comprising:

an SRAM test unit having a substantially same structure as a basic SRAM unit in the SRAM array;

a switch device connected to a power source, the SRAM test unit, and the SRAM array, wherein each of the SRAM test unit and the SRAM array is connected through the switch device to the power source; and

a switch control circuit connected to the SRAM test unit and the switch device and configured to, when a test voltage in the SRAM test unit is lower than a threshold voltage, close the switch device so that the power source begins to charge at least one of the SRAM array and the SRAM test unit through the switch device, wherein the SRAM array is configured be in a stable state when the SRAM test unit is in an unstable state.

2. The circuit of claim 1, wherein when a leakage voltage in the SRAM test unit is higher than the threshold voltage, the switch control circuit opens the switch device so that the power source no longer charges the SRAM array and the SRAM test unit.

3. The circuit of claim 1, wherein a supply voltage from the power source to the SRAM test unit is less than a supply voltage from the power source to the SRAM array, wherein the supply voltage to the SRAM test unit or the SRAM array is a voltage at a source of a P-type Metal-Oxide-Semiconductor (PMOS) transistor in a basic SRAM unit in the SRAM test unit or in a basic SRAM unit in the SRAM array.

4. The circuit of claim 1, wherein at least one of the following three conditions is true:

(a) the SRAM test unit is a basic SRAM unit in the SRAM array;

(b) the SRAM test unit is a backup basic SRAM unit of the SRAM array;

(c) the SRAM test unit and the SRAM array are in a same environmental temperature.

6. The circuit of claim 1, further comprising:

a leakage circuit connected to the SRAM test unit and the switch control circuit, wherein the leakage circuit is configured to leak current from the SRAM test unit.

7. The circuit of claim 6, wherein the leakage circuit comprises Complementary Metal-Oxide-Semiconductor (CMOS) transistors.

8. The circuit of claim 1, wherein the switch control circuit is a buffer.

9. The circuit of claim 1, further comprising:

a transistor electrically connected to an output node of an inverter of the SRAM test unit, wherein a gate of the transistor is electrically grounded.

10. The circuit of claim 1, wherein the switch device is an electric relay, a PMOS transistor, or an NMOS transistor.

11. The circuit of claim 1, wherein the switch device comprises a first switch connected to the power source and the SRAM test unit, and a second switch connected to the SRAM array and the first switch,

wherein the switch control circuit is connected to the first switch and the second switch and is configured to, when the test voltage of the SRAM test unit is less than the threshold voltage, close the first switch and the second switch so that the power source begins to charge the SRAM array and the SRAM test unit.

12. The circuit of claim 11, wherein at least one of the following two conditions is true:

(a) the first switch is an electric relay, a PMOS transistor, or an NMOS transistor;

(b) the second switch is an electric relay, a PMOS transistor, or an NMOS transistor.

13. The circuit of claim 1, wherein the switch control circuit comprises a first inverter and a second inverter that are serially connected.

14. The circuit of claim 13, wherein an input node of the first inverter is electrically connected to the SRAM test unit and is configured to receive the test voltage.

15. The circuit of claim 13, wherein the first inverter comprises a PMOS transistor, and wherein a source of the PMOS transistor is electrically connected to the power source.

16. The circuit of claim 13, wherein the first inverter comprises an NMOS transistor, and wherein a source of the NMOS transistor is electrically grounded.

17. The circuit of claim 13, further comprising:

a transistor, wherein a drain of the transistor is electrically connected to each of an output node of an inverter of the SRAM test circuit and an input node of the first inverter of the switch control circuit.

18. The circuit of claim 13, wherein the first inverter and a second inverter are serially connected between an output node of an inverter of the SRAM test unit and a gate of the switch device.

19. The circuit of claim 13, wherein the first inverter is connected through the second inverter to a gate of the switch device.

20. The circuit of claim 1, further comprising:

a first current path electrically connected between the switch device and the SRAM test unit, directly connected to a first terminal of the switch device, and directly connected to the SRAM test unit; and

a second current path electrically connected between the switch device and the SRAM array, directly connected to a second terminal of the switch device, directly connected to the SRAM array, and electrically insulated from the first current path.

5. A power supply circuit for a Static Random Access Memory (SRAM) array, the power supply circuit comprising:

an SRAM test unit having a substantially same structure as a basic SRAM unit in the SRAM array;

a switch device connected to a power source, the SRAM test unit, and the SRAM array, wherein each of the SRAM test unit and the SRAM array is connected through the switch device to the power source; and

a switch control circuit connected to the SRAM test unit and the switch device and configured to, when a test voltage in the SRAM test unit is lower than a threshold voltage, close the switch device so that the power source begins to charge at least one of the SRAM array and the SRAM test unit through the switch device; and

a closed switch, wherein the power source is connected to the SRAM test unit and the SRAM array and is configured to provide a current to the SRAM test unit and the SRAM array through the closed switch when the switch device is open.