Method and a device for measuring an analog voltage in a non-volatile memory

• US 6,507,183 B1
• Filed: 06/29/2000
• Issued: 01/14/2003
• Est. Priority Date: 07/02/1999
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Maccarrone, Marco, Mulatti, Jacopo
• Primary Examiner(s): Sherry, Michael
• Assistant Examiner(s): TANG, MINH NHUT
• Application Number:
  US09/608,847
• Time in Patent Office: 929 Days
• Field of Search: 324/99.D, 324/118, 324/139, 324/141, 324/170, 324/158.1, 365/185.03, 365/185.08, 365/185.11, 365/185.2, 365/189.02, 365/189.03, 365/189.09, 365/201, 365/244
• US Class Current: 324/99.00D
• CPC Class Codes: G11C 16/04 using variable threshold transistors, e.g. FAMOS
• CPC Class Codes: G11C 16/30 Power supply circuits
• CPC Class Codes: G11C 2029/5004 Voltage
• CPC Class Codes: G11C 29/02 Detection or location of defective auxiliary circuits, e.g. defective refresh counters
• CPC Class Codes: G11C 29/50 Marginal testing, e.g. race, voltage or current testing

Abstract

Presented is an analog voltage value measuring device for measuring any of a set of voltage references that are generated inside a memory architecture. The selected voltage to be measured is connected to a facility line through a multiplexer. The memory architecture includes a set of output buffers connected to a respective set of output pads. The device also includes a converter block, connected between the facility line and the output buffers of the memory architecture for converting a measured analog value of a voltage reference selected by the multiplexer to a digital value, which is presented on the output pads. A method of measuring an analog voltage value in a memory device is also disclosed. The method includes selecting an analog voltage value from the set of voltage values; transferring the selected analog value onto the facility line; converting the selected analog value to a digital value; and presenting the digital value on the output pads.

Claims

1. An analog voltage value measuring device in a memory architecture including a plurality of output buffers coupled to a corresponding plurality of output pads, the measuring device comprising:

a plurality of voltage generators structured to generate a plurality of voltage references;

a multiplexor coupled to the voltage generators and structured to connect a selected one of the voltage references to a facility line; and

a converter block connected between the facility line and the output buffers of the memory architecture and structured to convert a measured analog value of the selected voltage reference to a digital value and present the digital value on the plurality of output pads, to provide a measurement of the selected voltage reference.

2. The measuring device according to claim 1 wherein the converter block is a counter-ramp converter and includes:

a hysteresis comparator having an inverting input terminal coupled to the facility line and having an output terminal coupled to an n-bit counter through a series of a flip-flop and an enable logic gate structured to accept an enable signal.

3. The measuring device according to claim 2 wherein the n-bit counter is also structured to perform memory program and erase operations in the memory architecture.

4. The measuring device according to claim 2, wherein the presence of the enable signal is effective to disable the presentation of data from the n-bit counter to the output buffers.

5. The measuring device according to claim 2, further comprising a plurality of latch devices connected to outputs of the n-bit counter and structured to store obtained measurement data, and structured to allow the n-bit counter to disengage from the analog voltage measuring operation.

6. The measuring device according to claim 2 wherein the converter block further includes a digital-to-analog converter feedback connected between the n-bit counter and a non-inverting input terminal of the hysteresis comparator.

7. The measuring device according to claim 6, wherein the digital-to-analog converter includes:

a voltage divider connected between a first and a second voltage references, and connected, via a multiplexer, to an operational amplifier being supplied the first voltage reference and having a unity gain buffer configuration, the voltage divider structured to output a varying voltage signal within a predetermined range of values.

8. The measuring device according to claim 7, wherein the multiplexer includes a plurality of controlled passgates respectively connected to interconnection nodes of a plurality of resistive elements contained in the voltage divider, and structured to determine the varying value of the voltage signal within the predetermined range of values.

9. The measuring device according to claim 8, wherein the plurality of resistive elements all have a same resistive value.

10. The measuring device according to claim 8 wherein a conversion step of the digital-to-analog converter is determined by a number of the resistive elements contained in the voltage divider.

11. The measuring device according to claim 1, further comprising:

a non-volatile memory device that has been programmed with conversion bits anticipated for each of the plurality of analog voltages able to be measured, the non-volatile memory device coupled to a logic register which is in turn coupled between the converter block and the plurality of output buffers.

12. The measuring device according to claim 11, wherein the logic register is structured to compare a binary equivalent of the measured voltage value with an anticipated value stored in the non-volatile memory device, using a series of XNOR logic gates, and deliver the comparison results to the plurality of output buffers in the form of single bits.

13. The measuring device according to claim 12, further comprising:

a set of latch registers structured to store the results of a number of successive comparisons carried out by the logic register.

14. The measuring device according to claim 1, further comprising a sample-and-hold device, coupled between the multiplexer and the converter block, controlled by an external control signal, and structured to evaluate a settling time value of the selected analog voltage.

15. A method of statically measuring an analog voltage value in a memory device, comprising:

selecting an analog voltage value from a plurality of voltage values generated inside the memory device;

transferring the selected analog value onto a facility line;

converting the selected analog value to a digital value; and

presenting the digital value on a plurality of output pads of the memory device.

16. The measuring method according to claim 15 wherein selecting an analog voltage value from a plurality of voltage values comprises operating a multiplexer coupled between the plurality of voltage values and the facility line.

17. The measuring method according to claim 15 wherein converting the selected analog value to a digital value comprises utilizing a counter-ramp type of converter block comprising at least one n-bit counter.

18. The measuring method according to claim 17, wherein converting the selected analog value to a digital value is enabled by the presence of an enable signal being input to an enable logic gate contained in the converter block and connected to the n-bit counter.

19. The measuring method according to claim 17, wherein converting the selected analog value to a digital value comprises utilizing an n-bit counter in the memory device and structured as a state machine for programming and erasing cells within the memory device.

20. The measuring method according to claim 15, further comprising converting the digital value to a further analog value and inputting the further analog value to a converter block.

21. The measuring method according to claim 15, further comprising:

comparing the digital value to an anticipated value stored in a non-volatile memory device; and

presenting the result of the comparison, in the form of single bits, on output buffers being connected to the plurality of output pads.

22. The measuring method according to claim 21 wherein comparing the digital value to an anticipated value comprises using an XNOR type of logic scheme.

23. The measuring method according to claim 21, further comprising storing the results of a number of successive comparisons carried out for a number of selected analog voltages in a set of latch registers.

24. The measuring method according to claim 15, further comprising evaluating a settling time value of the selected analog voltage on a sample-and-hold device controlled by an external control signal.

25. An analog voltage measuring device for measuring an analog voltage, comprising:

a comparator having a first input terminal coupled to the analog voltage, a second input terminal coupled to a reference voltage, and an output;

a flip-flop having an input and an output, the input being coupled to the output of the comparator;

an n-bit counter having an input coupled to the output of the flip-flop and an output at which a digital value corresponding to the analog voltage is produced; and

a digital-to-analog converter having an input coupled to the output of the n-bit counter and an output coupled to the second input terminal of the comparator, the digital-to-analog converter being structured to convert the digital value at the output of the n-bit counter into the reference voltage.