WO2020240236A1 - Memory device with analog measurement mode features - Google Patents

Memory device with analog measurement mode features Download PDF

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Publication number
WO2020240236A1
WO2020240236A1 PCT/IB2019/000479 IB2019000479W WO2020240236A1 WO 2020240236 A1 WO2020240236 A1 WO 2020240236A1 IB 2019000479 W IB2019000479 W IB 2019000479W WO 2020240236 A1 WO2020240236 A1 WO 2020240236A1
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WIPO (PCT)
Prior art keywords
voltage
memory
current
input
state machine
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Ceased
Application number
PCT/IB2019/000479
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French (fr)
Inventor
Alberto TROIA
Antonino Mondello
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Micron Technology Inc
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Micron Technology Inc
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Filing date
Publication date
Application filed by Micron Technology Inc filed Critical Micron Technology Inc
Priority to PCT/IB2019/000479 priority Critical patent/WO2020240236A1/en
Priority to CN201980096982.XA priority patent/CN113906514B/en
Priority to DE112019007423.7T priority patent/DE112019007423T5/en
Priority to US16/625,371 priority patent/US11348655B2/en
Publication of WO2020240236A1 publication Critical patent/WO2020240236A1/en
Anticipated expiration legal-status Critical
Priority to US17/826,423 priority patent/US11728002B2/en
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/04—Detection or location of defective memory elements, e.g. cell constructio details, timing of test signals
    • G11C29/08—Functional testing, e.g. testing during refresh, power-on self testing [POST] or distributed testing
    • G11C29/12—Built-in arrangements for testing, e.g. built-in self testing [BIST] or interconnection details
    • G11C29/18—Address generation devices; Devices for accessing memories, e.g. details of addressing circuits
    • G11C29/30—Accessing single arrays
    • G11C29/32—Serial access; Scan testing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/02—Detection or location of defective auxiliary circuits, e.g. defective refresh counters
    • G11C29/021—Detection or location of defective auxiliary circuits, e.g. defective refresh counters in voltage or current generators
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/04—Detection or location of defective memory elements, e.g. cell constructio details, timing of test signals
    • G11C29/08—Functional testing, e.g. testing during refresh, power-on self testing [POST] or distributed testing
    • G11C29/12—Built-in arrangements for testing, e.g. built-in self testing [BIST] or interconnection details
    • G11C29/14—Implementation of control logic, e.g. test mode decoders
    • G11C29/16—Implementation of control logic, e.g. test mode decoders using microprogrammed units, e.g. state machines
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/04—Detection or location of defective memory elements, e.g. cell constructio details, timing of test signals
    • G11C29/08—Functional testing, e.g. testing during refresh, power-on self testing [POST] or distributed testing
    • G11C29/12—Built-in arrangements for testing, e.g. built-in self testing [BIST] or interconnection details
    • G11C29/36—Data generation devices, e.g. data inverters
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/56—External testing equipment for static stores, e.g. automatic test equipment [ATE]; Interfaces therefor
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C5/00—Details of stores covered by group G11C11/00
    • G11C5/14—Power supply arrangements, e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels
    • G11C5/143—Detection of memory cassette insertion or removal; Continuity checks of supply or ground lines; Detection of supply variations, interruptions or levels ; Switching between alternative supplies
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/04—Detection or location of defective memory elements, e.g. cell constructio details, timing of test signals
    • G11C29/08—Functional testing, e.g. testing during refresh, power-on self testing [POST] or distributed testing
    • G11C29/12—Built-in arrangements for testing, e.g. built-in self testing [BIST] or interconnection details
    • G11C29/18—Address generation devices; Devices for accessing memories, e.g. details of addressing circuits
    • G11C29/30—Accessing single arrays
    • G11C2029/3202—Scan chain
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/04—Detection or location of defective memory elements, e.g. cell constructio details, timing of test signals
    • G11C29/50—Marginal testing, e.g. race, voltage or current testing
    • G11C2029/5004—Voltage
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C29/00—Checking stores for correct operation ; Subsequent repair; Testing stores during standby or offline operation
    • G11C29/04—Detection or location of defective memory elements, e.g. cell constructio details, timing of test signals
    • G11C29/50—Marginal testing, e.g. race, voltage or current testing
    • G11C2029/5006—Current

Definitions

  • the present disclosure relates in general to apparatuses and methods for memory management and more particularly to a memory device structured with internal analogic measurement mode features.
  • the memory device is a non volatile memory component that is coupled to a host device or to a System-on- Chip.
  • Non-volatile Flash memories are today one of the fundamental building blocks in modern electronic systems, including the SoC devices for automotive applications, in particular for Real Time Operating Systems (RTOS). Their performance in terms of speed, consumption, alterability, nonvolatility and the increasing importance of system reconfigurability have pushed up to now for flash memory integration in System-on-Chip (SoC) devices.
  • SoC System-on-Chip
  • a further need would be that of providing non-volatile memory devices including features for performing various measurements of the flash memory array.
  • the measurement mode of a flash array can contain reserved operation that only the supplier of the component would like to use.
  • a JTAG protocol teaches already how to implement hardware and algorithms to perform proper memory measuring.
  • conventional JTAG is relatively slow for memory devices having a large size.
  • Figure 1 is a schematic view of a known digital low voltage detector for memory components realized according to a prior art solution
  • Figure 1A shows a first and a second diagram reporting a measurement of voltage value Vx affected by noise and more regular and stable value, respectively;
  • Figure 2A shows a schematic view of a memory device associated to a host device or a System-on-Chip according to embodiments of the present disclosure
  • Figure 2B shows a schematic view of a hardware block incorporated into the memory device of the present disclosure to provide internal analogic measurement mode features
  • Figure 3 is a schematic view of a first embodiment of the hardware block of Figure 2B and according to the present disclosure
  • Figure 4 is a diagram showing a measurement of a voltage value Vx obtained with the block of Figure 3;
  • Figure 5 is a schematic view of an alternative embodiment of the hardware block of Figure 2B according to the present disclosure.
  • Figure 6 is a diagram showing a measurement of a current value lx obtained with the block of Figure 5; [017] Figure 7 shows a block diagram of a method according to the present disclosure.
  • Memory devices are frequently provided as internal, semiconductor, integrated circuits and/or external removable devices in computers or other electronic devices.
  • memory There are many different types of memory, including volatile and non-volatile memory.
  • Volatile memory including random-access memory (RAM), static random access memory (SRAM), dynamic random access memory (DRAM), and synchronous dynamic random access memoiy (SDRAM), among others, may require a source of applied power to maintain its data.
  • RAM random-access memory
  • SRAM static random access memory
  • DRAM dynamic random access memory
  • SDRAM synchronous dynamic random access memoiy
  • Non-volatile memory by contrast, can retain its stored data even when not externally powered.
  • Non-volatile memory is available in a wide variety of technologies, including flash memory (e.g., NAND and NOR), Read Only Memory (ROM), Electrically Erasable Programmable ROM (EEPROM), Erasable Programmable ROM (EPROM), and resistance variable memoiy such as phase change random access memory (PC RAM), self-selecting chalcogenide-based memories, resistive random access memory (RRAM), 3D XPoint memory (3DXP) and magneto-resistive random access memory (MRAM), among others.
  • flash memory e.g., NAND and NOR
  • ROM Read Only Memory
  • EEPROM Electrically Erasable Programmable ROM
  • EPROM Erasable Programmable ROM
  • PC RAM phase change random access memory
  • RRAM resistive random access memory
  • 3DXP 3D XPoint memory
  • MRAM magneto-resistive random access memory
  • Memory devices can include large arrays of memory cells for storing data, frequently organized into rows and columns. Individual memory cells and/or ranges of memory cells can be addressed by their row and column. When a memory array is addressed, there may be one or more layers of address translation, to e.g., translate between a logical address utilized by a host device and a physical address corresponding to a location in the memory array.
  • Some of these circuit blocks need to receive signals reporting voltage and/or current values detected in the memory component for correctly driving the reading, programming or erasing phases of the memory array More specifically, these circuit blocks need to have the power supply and signals advising that the power supply is correct. For instance, the signal can be a result of a comparison between a BandGap reference voltage, with proper voltage scale, and the external supply. This signal information is driven to the memory internal controller to execute correctly the required operation following a firmware. Similar consideration may be done with respect to a reference current.
  • the required voltage and/or current value are detected by specific circuit portions that operates as voltage or current detectors.
  • Flash memory device is very sensitive to the power supply when it programs and erases the memory array in particular for data retention issues and for the reliability.
  • the Flash array must be a very high reliable device able also to inform the SoC that something wrong is happening with the power supply. This task is assigned to a controller of the flash array (not shown) that is incorporated into the memory component.
  • known standard voltage or current detectors are noise sensitive.
  • a voltage or current detector to be used in a memory component coupled to a host device or embedded/ associated to a System-on-Chip having a low sensitivity to a possible noise disturbing the measurement.
  • the detector disclosed herewith provides just the value of the detected measurement protecting the manner in which the detector has obtained such a measurement, thus protecting the memory portion from possible hacker attack or reverse engineering in order to get some technological parameters.
  • a further feature of the detector of the present disclosure is given by the capability of generating reference voltage or currents according to the operating needs of the memory portion wherein the detector has been incorporated.
  • Figure 1 shows a schematic example of a prior art solution for detecting a low voltage value in a memory portion, for instance a memory portion embedded in a complex System-on-Chip.
  • the detector shown in Figure 1 is based on a Schmitt trigger comparator 100 receiving on one input the output of a digital to analogic or analog (D/A) converter 1 10.
  • D/A digital to analogic or analog
  • This D/A converter 1 10 is coupled to a stable reference voltage potential Vrif generated for instance by an analogic bandgap generator with a proper configuration, i.e. a proper conversion factor, (not shown in the figures) and is driven by a digital input configuration signal Config.
  • a sample and hold block 120 receives as input a voltage value Vx to be measured and applies its output to the other non-inverting input of the Schmitt trigger 1 10.
  • the Schmitt trigger is a comparator circuit with hysteresis implemented by applying positive feedback to the non-inverting input of a comparator or differential amplifier. It is an active circuit which converts an analog input signal to a digital output signal. The circuit is considered a trigger because the output retains its value until the input changes sufficiently to trigger a change. In the non-inverting configuration, when the input is higher than a chosen threshold, the output is high. When the input is below a different (lower) chosen threshold the output is low, and when the input is between the two levels the output retains its value.
  • Figure 1A shows a first diagram reporting the variations of the input voltage Vx because of the noise disturbing the measurement and a second diagram reporting a stable voltage value Vx that remains within a small range represented by a higher voltage value Vh and a lower voltage value VI.
  • Flash array measuring needs some measurement modes that involves: reference current generation; reference voltage generation.
  • an internal analogic measurement mode structure is implemented in a single analogic block 200 managed using the JTAG interface.
  • the analogic block 200 is substantially a hardware block incorporated into a circuit portion of a non-volatile memory device 1.
  • the memory device 1 is shown in Figure 2A and includes an array 6 of Flash memory cells and a circuitry located around the memory array.
  • the memory array 6 includes a non-volatile memory portion, NAND Flash or NOR Flash.
  • Such a memory device 1 is an independent structure but it is a component strictly associated to a host device 10 or to a System- on- Chip. More particularly, the memory device 1 is associated and linked to the SoC structure 10 partially overlapping such a structure while the corresponding semiconductor area of the SoC structure has been used for other logic circuits. The coupling between the SoC structure and the memory component is obtained by interconnecting a plurality of respective pads or pin terminals that are faced one toward the other (not shown).
  • the pads of the memory component have been realized on a surface of the memory component, in practice on the top of the array. More specifically, the pads are arranged over the array so that, when the memory component 1 is reversed or flipped, its pads are faced to corresponding pads of the host or SoC structure in a circuit layout that keeps the alignment of the pads with a technology similar to Flip- Chip. Other coupling techniques may be used.
  • the Flash memory component 1 includes at least: an I/O circuit 5, a micro sequencer 3, an array of memory cells 6, voltage and current reference generators 7, charge pumps 2 and decoding circuitry 8, sense amplifiers 9 and corresponding latches, a command user interface, for instance a CUI block 4; some of all of the circuitry may be located at the array periphery or under the array, depending on the manufacturing technology.
  • the micro-sequencer 3 is substantially a memory controller that is coupled to the memory array 6.
  • a controller can be a microcontroller, special purpose logic circuitry such as a Filed programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC) or other suitable processor.
  • FPGA Filed programmable Gate Array
  • ASIC Application Specific Integrated Circuit
  • the memory component 1 also comprises a JTAG logic, for instance a JTAG interface adopted for the measurement and/or the test of the memory component 1 and allowing the re-use of measurement tooling.
  • a JTAG logic for instance a JTAG interface adopted for the measurement and/or the test of the memory component 1 and allowing the re-use of measurement tooling.
  • Figure 2B shows a schematic view of a hardware block incorporated into the memory device of the present disclosure to provide internal analogic measurement mode features.
  • the analogic block 200 is managed by using the JTAG interface.
  • control signals are T_Reg bits contained in a special instruction register of the JTAG interface.
  • a JTAG interface of the memory component 1 may be completed by additional registers that may be used as shift data registers for allowing the interaction with the core of the host device 10 for instance in the writing and/or reading phases of the memory component.
  • micro sequencer or controller 3 comprises an interface with a plurality of measurement or test registers (in the following globally indicated as T_reg), each register being associated with a specific address (known as T_reg_addr), for testing the functionality of the memoiy component to which the controller is associated, or generally for interfacing the memory component with a testing machine and/or an external core.
  • T_reg measurement or test registers
  • T_reg_addr a specific address
  • the measurement mode architecture of the memory component is therefore based on these registers, which, under certain circumstances, can be written/read by the SoC controller via JTAG interface, by the test machine via JTAG interface, and by the flash array controller 3 via internal buses.
  • test registers T_reg contain the instructions (e.g. parameters such as currents/voltages) for the measurement and/or test of the memory component.
  • N 8, 16, etc..
  • Each bank is also apt to drive one or more macro function (Analog or Digital).
  • the measurement and/or test of the memory component is therefore managed by a protocol based on a JTAG interface using the instructions of the test registers T_reg.
  • the measurement and/or test can be controlled by the SoC core or controller or by an external test machine.
  • both the approaches are based on a Built-In Self-Test (BIST) executed by the internal flash array controller 3 of the present disclosure. This approach also maintains secret the internal algorithm with sensitive technological parameters (such as timing voltages and the like).
  • test registers T_reg can be accessed by an external user, and a filtering block (not shown) in the controller 3 is configured to disable the access to some test registers T_reg based on a RUA signal generated by the processing unit. In other words, in some embodiments access to a subset of a plurality of test registers is limited.
  • the filtering block is configured in such a way that, when the RUA signal is generated by the processing unit; some reserved registers are not addressable by masking the specific address of such register, and the output of said filtering block yields only the first allowed register T_reg.
  • test registers T_reg that are not addressable are written by the controller 3 in a configuration register.
  • One embodiment of the present disclosure relates to a memory device with analog measurement mode features including: at least a memory component with a memory array; a memory controller coupled to the memory component; a JTAG interface in said memory controller; voltage and current reference generators;
  • the memory device of the present disclosure further comprises a plurality of test registers in said JTAG interface, each register being associated with a specific address for testing the functionality of the memory component to which the controller is associated.
  • the analogic measurement mode block 200 shown in Figure 2B includes also the voltage and current reference generators of the memory device.
  • This block 200 receives as inputs a fixed reference voltage value, for instance a Vref (band gap).
  • a further input is represented by the I_V_Value that indicates the value of the current If or voltage Vf to be generated.
  • the schematic arrow indicating plural command signals represent a series of instructions received by the block 200 for providing various measurements, for instance: Measure Vx, Measure lx, or for generating voltage or current values, for instance: Generate Vf, Generate If, or for other instructions.
  • Vx or lx are analogic voltage and current values to be measured, while Vf and If are programmable reference values.
  • a clock input CLK serves as a clock an internal FSM disclosed later.
  • Figure 3 is a schematic view of a first embodiment of the hardware block of Figure 2B and according to the present disclosure. In this Figure the depicted current-to -voltage converter is not used during voltage measurement or generation.
  • the block 200 includes a low voltage detector comprising: a comparator 180 receiving on a voltage input a voltage value to be detected;
  • a digital to analog converter 1 10 coupled to a reference voltage potential and having an output connected to other input of said comparator; a Finite State Machine 210 receiving the output of said comparator and producing digital outputs for the inputs of said memory controller.
  • the D/A converter 1 10 is coupled to a stable reference voltage potential Vref generated for instance by an analogic bandgap generator and receives a digital input signal Count.
  • the reference voltage Vref (band gap) is to be considered as an external voltage value.
  • a normal value for a bandgap reference could be about 1.2 Volt even if this value is just indicative.
  • a different stable voltage generator may be used to provide Vref.
  • the comparator 180 has a second inverting (-) input receiving the voltage value Vx to be measured.
  • the example reported herewith should be considered as a schematic indication that the inverting input of the comparator 180 is connected to a node point or to a terminal of the memory portion or component wherein a voltage potential Vx is applied and such a potential must be measured with great precision obtaining a value not affected by noise.
  • the Finite State Machine 210 is a complex logic portion capable to execute algorithms. In the subsequent part of the present disclosure we will provide an example of an algorithm executed by the Finite State Machine 210.
  • This Finite State Machine 210 operates according to a clock signal CLK of the memory component and received on one input.
  • the FSM receives also as a further input a Command signal issued by the internal memory controller to execute properly the operation that the internal firmware can require depending on the access phase to the memory array.
  • the command signal may arrive from a host device coupled to the memory component or issued by a controller of the System-on-Chip hosting the embedded memory component
  • a multiplexer 150 is provided between the Finite State Machine 210 and the digital input of the D/A converter 1 10.
  • a selection signal SEL is produced by the Finite State Machine 210 to drive the multiplexer 150 and select the proper path for the input signal to the output of the multiplexer.
  • the output of the multiplexer 150 is a Count digital input for the D/A converter 1 10.
  • This multiplexer 150 receives as a first input a logic value corresponding to a voltage or a current measurement and on a second input the output of the Finite State Machine 210.
  • the output value of the comparator 180 is applied as a feedback input to the Finite State Machine 210. This output value Vf is outputted when it is greater than a voltage value Vx to be measured.
  • the output value Vf of the comparator 180 is triggered when the voltage value Vf is greater than the voltage value Vx to be measured.
  • a current- to-voltage converter 130 is depicted also in Figure 3, however it is not used during voltage detection and measurement nor during reference voltage generation. Converter 130 and its functionality will be described below with reference to current detection and measurement and reference current generation.
  • the Finite State Machine 210 is settable with a programmable Time_out value that represents the max duration of the time interval for performing the measurement of the voltage value Vx.
  • Finite State Machine 210 finds the value in a sequential manner or, as an alternative, in a dichotomic way or with any other method that can speed up the finding of the final value.
  • the detected voltage value Vx remains substantially stable within an upper limit Vrif * Count_H and a lower limit Vrif * Count-L.
  • the window delimited by the upper and lower voltage limits of the time interval DT is programmable by the user of the memory component.
  • the FSM 210 is always capable to detect the possible presence of noise since the detected voltage value Vx must remain within the upper and lower limits above reported and when the detected value is outside the expected range, like for instance in the portion of the diagram indicated by the number 190, the measurement is repeated automatically.
  • Figure 4 is a diagram showing a measure of a voltage value Vx obtained with the block of Figure 3. As shown in the diagram of Figure 4, during the time interval DT the detected voltage value lx remains substantially stable within an upper limit Vrif * Count_H and a lower limit Vrif * Count-L. The window delimited by the upper and lower voltage limits of the time interval DT is programmable by the user of the memory component.
  • the FSM is always capable to detect the possible presence of noise since the detected voltage value Vx must remain within the upper and lower limits above reported and when the detected value is outside the expected range, like for instance in the portion of the diagram indicated by the number 190, the measurement is repeated automatically.
  • the numeric value N represents the maximum number of attempts that the detector should perform for obtaining the required measured value Vx.
  • the other time TO, T1 and T2 are time parameters measured from a common origin
  • the reported parameters N, TO, Tl , T2 are all programmable in the sense that their value may be set according to the quality and reliability of the measurement to be performed. Even the time interval DT is a parameter that may be programmed.
  • the detector of the present disclosure may be used for measuring also a current value, for instance a current value lx.
  • Figure 5 is a schematic view of an alternative embodiment of the hardware block of Figure 2B according to the present disclosure and more specifically for current measurements.
  • Several elements in figure 5 are the same as those of figure 3 described above; however, some of them (such as voltage comparator 180) are not used during operation as current detection and measurement and reference current generation as better explained below.
  • the basic portion of the detector disclosed herewith is structured in a similar fashion as the detector described with reference to Figure 3; however, instead of voltage comparator 180 a converter 130 from current to voltage is used.
  • the structure of this converter 130 is based on a current mirror including a differential cell 140 comprising PMOS and NMOS transistors.
  • One input of the current mirror is the current value lx to be measured.
  • current input terminal of the converter 130 corresponds to a node point or to a terminal of the memory portion or component wherein a current value lx is flowing and such a current value must be measured with great precision obtaining a value not affected by noise.
  • the current to voltage converter has an input node on a first leg coupled to a node of a circuit in the memory component, the circuit configured to drain the current lx.
  • the differential cell 140 of the current mirror includes a first leg associated to the input current value lx and a second leg associated to the output of the D/A converter 1 10.
  • the output of the D/A converter 1 10 is applied to a gate of an NMOS transistor of the second current mirror leg draining a reference current If.
  • the voltage value Vf at the output of the D/A converter is proportional to the reference voltage Vref (band gap) and is further applied to the gate terminal of a buffer transistor TR having conducting terminal linked between the reference current If node and a ground potential reference.
  • Transistor TR further mirrors the current Iref in the second leg of the current- to-voltage converter 130, making it possibly available at its drain node.
  • the output of the voltage or current detector of the present disclosure is represented by a digital output of the FSM wherein a digital value I_Vmeasured [M:0] is presented to the outside world, for instance the SoC controller.
  • the Finite State Machine 210 receives as input an output value If outputted by the converter 130 and is capable to issue digital values for the input of the D/A converter 1 10.
  • the multiplexer 150 receives as input the signal output of the FSM 210 and as a further input a digital current /voltage value I_V_value .
  • the Finite State Machine 210 may execute to measure a current value lx.
  • the algorithm includes a list of instructions and parameters that have been adopted for reaching the required measurement.
  • N max measures attempt Wait (TO) u- second (lx is hopefully a stable value)
  • the FSM looking for the counter value that provides If ⁇ Ix Count_H ⁇ - counter counter - 1
  • the numeric value N represents the maximum number of attempts that the detector should perform for obtaining the required measured value lx.
  • the other time TO, T1 and T2 are time parameters measured from a common origin.
  • a is a conversion factor from voltage to current (e.g., such that Vrif*Count_L*a corresponds to Irif*Count_L and Vrif*Count_H*a corresponds to Irif*Count_H).
  • the window delimited by the upper and lower current limits of the time interval DT is programmable by the user of the memory component.
  • the FSM is always capable to detect the possible presence of noise since the detected current value lx must remain within the upper and lower limits above reported and when the detected value is outside the expected range, like for instance in the portion of the diagram indicated by the number 290, the measurement is repeated automatically.
  • One embodiment of the present disclosure relates to a method to operate a memory device including at least a memory array and a memory controller, the method comprising:
  • Figure 7 shows a block diagram of a method 700 according to the present disclosure.
  • Method 700 comprises, at block 710 driving by the memory controller an analogic measurement block through a JTAG interface.
  • the driving may be carried out according to the embodiments described above with reference to figures 1 to 6.
  • commands may be issued to Finite State Machine 210 by the JTAG interface in controller 3.
  • Method 700 comprises, at block 720, generating voltage and/or current reference values based on the driving.
  • the generating voltage and/or current may be implemented by Current/Voltage generation and measurement block 200 described in Figure 2B and in more details 3 and 5, for example.
  • Method 700 further comprises, at block 730, detecting that the generated voltage and/or current is correct.
  • Generated voltage or current detection may be implemented by the circuits described in figures 3 and 5, in some embodiments.
  • Method 700 may further comprise generating instructions by at least a test register of said JTAG interface for said analogic measurement block.
  • method 700 may also comprise limiting access to a subset of a plurality of test registers, as described above.
  • method 700 comprises applying to an input of a comparator a voltage value Vx to be detected and/or applying to an input of a current to voltage converter a current value lx to be detected.
  • Method 700 may also comprise feeding the comparator output and the current to voltage converter output to corresponding inputs of a Finite State Machine and applying digital outputs of said Finite State Machine to a digital to analog converter coupled to a reference voltage potential and having an output connected to another input of said comparator for detecting an average voltage value or an average current value in a time interval
  • One of the advantage of the method of the present disclosure is given by the presence of a on board mechanism for measuring voltage values V and current values I related to the flash array without exposing the cells terminal to any contact from an external component, for instance a host device or a SoC to whom the memory is associated.
  • This feature has the great advantage to permit to protect some technological secret not directly measurable from outside the memory component thus rendering the memory device more robust against attacks directed to detect process parameter hacking direct measurement on flash cells.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Tests Of Electronic Circuits (AREA)
  • For Increasing The Reliability Of Semiconductor Memories (AREA)

Abstract

The present disclosure relates to apparatuses and methods for memory management and more particularly to a memory device structured with internal analogic measurement mode features. The memory is provided with means for detecting a correct generation of voltage and/or current reference values in the memory device including at least a memory array and a memory controller. The method provides for a JTAG interface in the memory controller and an analogic measurement block in said memory device driven by said JTAG interface.

Description

MEMORY DEVICE WITH ANALOG MEASUREMENT MODE FEATURES
DESCRIPTION
TECHNICAL FIELD
[001] The present disclosure relates in general to apparatuses and methods for memory management and more particularly to a memory device structured with internal analogic measurement mode features. The memory device is a non volatile memory component that is coupled to a host device or to a System-on- Chip.
[002] BACKGROUND
[003] Non-volatile Flash memories are today one of the fundamental building blocks in modern electronic systems, including the SoC devices for automotive applications, in particular for Real Time Operating Systems (RTOS). Their performance in terms of speed, consumption, alterability, nonvolatility and the increasing importance of system reconfigurability have pushed up to now for flash memory integration in System-on-Chip (SoC) devices.
[004] However, with the current technologies the embedded memory portion is becoming the largest circuit portion in a SoC and it is not appropriate to increase their size to more than 128Mbit since it is very difficult to manage the whole embedded memory structure when the lithography node is below 28nm.
[005] In many applications it would be highly desirable to enlarge the size of the memory portion but it would be necessary to provide a new manner of coupling the SoC and the embedded or associated memory component. Moreover, it would be necessary to provide a more efficient manner to exchange signals and measured values between the memory portion and the controller of the SoC.
[006] In this respect a further need would be that of providing non-volatile memory devices including features for performing various measurements of the flash memory array. However, the measurement mode of a flash array can contain reserved operation that only the supplier of the component would like to use. [007] A JTAG protocol teaches already how to implement hardware and algorithms to perform proper memory measuring. However, conventional JTAG is relatively slow for memory devices having a large size.
[008] Moreover, it would be highly desirable to provide internal analogic measurement mode features ensuring that only the right authority can access to specific measurement modes and/or to the update of the internal Flash array controller. The present disclosure is focused on the solution of the above- mentioned needs.
BRIEF DESCRIPTION OF THE DRAWINGS
[009] - Figure 1 is a schematic view of a known digital low voltage detector for memory components realized according to a prior art solution;
[010] Figure 1A shows a first and a second diagram reporting a measurement of voltage value Vx affected by noise and more regular and stable value, respectively;
[Oi l] Figure 2A shows a schematic view of a memory device associated to a host device or a System-on-Chip according to embodiments of the present disclosure;
[012] Figure 2B shows a schematic view of a hardware block incorporated into the memory device of the present disclosure to provide internal analogic measurement mode features;
[013] Figure 3 is a schematic view of a first embodiment of the hardware block of Figure 2B and according to the present disclosure;
[014] Figure 4 is a diagram showing a measurement of a voltage value Vx obtained with the block of Figure 3;
[015] Figure 5 is a schematic view of an alternative embodiment of the hardware block of Figure 2B according to the present disclosure;
[016] Figure 6 is a diagram showing a measurement of a current value lx obtained with the block of Figure 5; [017] Figure 7 shows a block diagram of a method according to the present disclosure.
DETAILED DESCRIPTION
[018] In the following detailed description, reference is made to the accompanying drawings that form a part hereof and in which is shown, by way of illustration, specific embodiments. In the drawings, like numerals describe substantially similar components throughout the several views. Other embodiments may be disclosed and structural, logical, and electrical changes may be made without departing from the scope of the present disclosure. The following detailed description is, therefore, not to be taken in a limiting sense.
[019] Memory devices are frequently provided as internal, semiconductor, integrated circuits and/or external removable devices in computers or other electronic devices. There are many different types of memory, including volatile and non-volatile memory. Volatile memory, including random-access memory (RAM), static random access memory (SRAM), dynamic random access memory (DRAM), and synchronous dynamic random access memoiy (SDRAM), among others, may require a source of applied power to maintain its data. Non-volatile memory, by contrast, can retain its stored data even when not externally powered.
[020] Non-volatile memory is available in a wide variety of technologies, including flash memory (e.g., NAND and NOR), Read Only Memory (ROM), Electrically Erasable Programmable ROM (EEPROM), Erasable Programmable ROM (EPROM), and resistance variable memoiy such as phase change random access memory (PC RAM), self-selecting chalcogenide-based memories, resistive random access memory (RRAM), 3D XPoint memory (3DXP) and magneto-resistive random access memory (MRAM), among others.
[021] Memory devices can include large arrays of memory cells for storing data, frequently organized into rows and columns. Individual memory cells and/or ranges of memory cells can be addressed by their row and column. When a memory array is addressed, there may be one or more layers of address translation, to e.g., translate between a logical address utilized by a host device and a physical address corresponding to a location in the memory array.
[022] For the regular operation of the memory array it is necessary to provide to the memory measured voltage and current values for managing the reading, writing and erasing phases of the memory cells. Moreover, it would be highly desirable to provide internal analogic measurement mode features ensuring that only the right authority can access to specific measurement modes and/or to the update of the internal Flash array controller.
[023] For a better understanding of the present disclosure, let’s consider for instance a flash memory device coupled to a host device or associated to a SoC and including some circuit blocks shared with the SoC, for instance the read logic to implement the fetch /prefetch scheme and-or the branch prediction.
[024] Some of these circuit blocks need to receive signals reporting voltage and/or current values detected in the memory component for correctly driving the reading, programming or erasing phases of the memory array More specifically, these circuit blocks need to have the power supply and signals advising that the power supply is correct. For instance, the signal can be a result of a comparison between a BandGap reference voltage, with proper voltage scale, and the external supply. This signal information is driven to the memory internal controller to execute correctly the required operation following a firmware. Similar consideration may be done with respect to a reference current.
[025] The required voltage and/or current value are detected by specific circuit portions that operates as voltage or current detectors.
[026] A Flash memory device is very sensitive to the power supply when it programs and erases the memory array in particular for data retention issues and for the reliability. The Flash array must be a very high reliable device able also to inform the SoC that something wrong is happening with the power supply. This task is assigned to a controller of the flash array (not shown) that is incorporated into the memory component. [027] Unfortunately, known standard voltage or current detectors are noise sensitive.
[028] The current /voltage under measurement cannot be stable during the measurement time frame. Therefore, the measurement could be not accurate.
[029] In some embodiments it is provided a voltage or current detector to be used in a memory component coupled to a host device or embedded/ associated to a System-on-Chip having a low sensitivity to a possible noise disturbing the measurement.
[030] In some cases the detector disclosed herewith provides just the value of the detected measurement protecting the manner in which the detector has obtained such a measurement, thus protecting the memory portion from possible hacker attack or reverse engineering in order to get some technological parameters.
[031] A further feature of the detector of the present disclosure is given by the capability of generating reference voltage or currents according to the operating needs of the memory portion wherein the detector has been incorporated.
[032] Figure 1 shows a schematic example of a prior art solution for detecting a low voltage value in a memory portion, for instance a memory portion embedded in a complex System-on-Chip.
[033] The detector shown in Figure 1 is based on a Schmitt trigger comparator 100 receiving on one input the output of a digital to analogic or analog (D/A) converter 1 10.
[034] This D/A converter 1 10 is coupled to a stable reference voltage potential Vrif generated for instance by an analogic bandgap generator with a proper configuration, i.e. a proper conversion factor, (not shown in the figures) and is driven by a digital input configuration signal Config.
[035] According to the value of the digital input configuration signal the D/A converter 1 10 provides a modulated output value. [036] A sample and hold block 120 receives as input a voltage value Vx to be measured and applies its output to the other non-inverting input of the Schmitt trigger 1 10.
[037] The Schmitt trigger is a comparator circuit with hysteresis implemented by applying positive feedback to the non-inverting input of a comparator or differential amplifier. It is an active circuit which converts an analog input signal to a digital output signal. The circuit is considered a trigger because the output retains its value until the input changes sufficiently to trigger a change. In the non-inverting configuration, when the input is higher than a chosen threshold, the output is high. When the input is below a different (lower) chosen threshold the output is low, and when the input is between the two levels the output retains its value.
[038] The output obtained from the Schmitt trigger is the voltage value Vx > Vrif * Config.
[039] This structure however is very sensitive to supply variations because of its intrinsic Schmidt trigger configuration.
[040] For example, Figure 1A shows a first diagram reporting the variations of the input voltage Vx because of the noise disturbing the measurement and a second diagram reporting a stable voltage value Vx that remains within a small range represented by a higher voltage value Vh and a lower voltage value VI.
[041] It would be desirable to obtain a stable measurement of the voltage value Vx as shown by the second diagram and the detector of the present disclosure is structured to obtain such a result.
[042] Moreover, Flash array measuring needs some measurement modes that involves: reference current generation; reference voltage generation. [043] According to embodiments of the present disclosure an internal analogic measurement mode structure is implemented in a single analogic block 200 managed using the JTAG interface.
[044] The analogic block 200 is substantially a hardware block incorporated into a circuit portion of a non-volatile memory device 1.
[045] The memory device 1 is shown in Figure 2A and includes an array 6 of Flash memory cells and a circuitry located around the memory array. The memory array 6 includes a non-volatile memory portion, NAND Flash or NOR Flash.
[046] Such a memory device 1 is an independent structure but it is a component strictly associated to a host device 10 or to a System- on- Chip. More particularly, the memory device 1 is associated and linked to the SoC structure 10 partially overlapping such a structure while the corresponding semiconductor area of the SoC structure has been used for other logic circuits. The coupling between the SoC structure and the memory component is obtained by interconnecting a plurality of respective pads or pin terminals that are faced one toward the other (not shown).
[047] The pads of the memory component have been realized on a surface of the memory component, in practice on the top of the array. More specifically, the pads are arranged over the array so that, when the memory component 1 is reversed or flipped, its pads are faced to corresponding pads of the host or SoC structure in a circuit layout that keeps the alignment of the pads with a technology similar to Flip- Chip. Other coupling techniques may be used.
[048] The Flash memory component 1 includes at least: an I/O circuit 5, a micro sequencer 3, an array of memory cells 6, voltage and current reference generators 7, charge pumps 2 and decoding circuitry 8, sense amplifiers 9 and corresponding latches, a command user interface, for instance a CUI block 4; some of all of the circuitry may be located at the array periphery or under the array, depending on the manufacturing technology.
[049] The micro-sequencer 3 is substantially a memory controller that is coupled to the memory array 6. Such a controller can be a microcontroller, special purpose logic circuitry such as a Filed programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC) or other suitable processor.
[050] The memory component 1 also comprises a JTAG logic, for instance a JTAG interface adopted for the measurement and/or the test of the memory component 1 and allowing the re-use of measurement tooling.
[051] Figure 2B shows a schematic view of a hardware block incorporated into the memory device of the present disclosure to provide internal analogic measurement mode features. In one embodiment of the present disclosure the analogic block 200 is managed by using the JTAG interface.
[052] More particularly, the control signals are T_Reg bits contained in a special instruction register of the JTAG interface.
[053] According to the IEEE1 149 and IEEE1532 standards a JTAG interface of the memory component 1 may be completed by additional registers that may be used as shift data registers for allowing the interaction with the core of the host device 10 for instance in the writing and/or reading phases of the memory component.
[054] However, depending on the command loaded in the IR, different registers can be combined. In this respect, the present disclosure suggests adopting a special register T_Reg including instructions to perform the analogic measurement of the analogic components of the memory device 1.
[055] Furthermore, according to an embodiment of the present disclosure, micro sequencer or controller 3 comprises an interface with a plurality of measurement or test registers (in the following globally indicated as T_reg), each register being associated with a specific address (known as T_reg_addr), for testing the functionality of the memoiy component to which the controller is associated, or generally for interfacing the memory component with a testing machine and/or an external core. [056] The measurement mode architecture of the memory component is therefore based on these registers, which, under certain circumstances, can be written/read by the SoC controller via JTAG interface, by the test machine via JTAG interface, and by the flash array controller 3 via internal buses.
[057] The test registers T_reg contain the instructions (e.g. parameters such as currents/voltages) for the measurement and/or test of the memory component.
[058] In particular, test registers are organized in several banks each containing N registers (N=8, 16, etc..) and being associated with a specific address TL_addr. Each bank is also apt to drive one or more macro function (Analog or Digital).
[059] The measurement and/or test of the memory component is therefore managed by a protocol based on a JTAG interface using the instructions of the test registers T_reg. As previously observed, the measurement and/or test can be controlled by the SoC core or controller or by an external test machine. In any case, both the approaches are based on a Built-In Self-Test (BIST) executed by the internal flash array controller 3 of the present disclosure. This approach also maintains secret the internal algorithm with sensitive technological parameters (such as timing voltages and the like).
[060] Not all the test registers T_reg can be accessed by an external user, and a filtering block (not shown) in the controller 3 is configured to disable the access to some test registers T_reg based on a RUA signal generated by the processing unit. In other words, in some embodiments access to a subset of a plurality of test registers is limited.
[061] In this embodiment, the filtering block is configured in such a way that, when the RUA signal is generated by the processing unit; some reserved registers are not addressable by masking the specific address of such register, and the output of said filtering block yields only the first allowed register T_reg.
[062] The test registers T_reg that are not addressable are written by the controller 3 in a configuration register. [063] One embodiment of the present disclosure relates to a memory device with analog measurement mode features including: at least a memory component with a memory array; a memory controller coupled to the memory component; a JTAG interface in said memory controller; voltage and current reference generators;
- an analogic measurement mode block driven by said JTAG interface.
[064] The memory device of the present disclosure further comprises a plurality of test registers in said JTAG interface, each register being associated with a specific address for testing the functionality of the memory component to which the controller is associated.
[065] The analogic measurement mode block 200 shown in Figure 2B includes also the voltage and current reference generators of the memory device.
[066] This block 200 receives as inputs a fixed reference voltage value, for instance a Vref (band gap). A further input is represented by the I_V_Value that indicates the value of the current If or voltage Vf to be generated.
[067] The schematic arrow indicating plural command signals represent a series of instructions received by the block 200 for providing various measurements, for instance: Measure Vx, Measure lx, or for generating voltage or current values, for instance: Generate Vf, Generate If, or for other instructions.
[068] The values Vx or lx are analogic voltage and current values to be measured, while Vf and If are programmable reference values.
[069] A clock input CLK serves as a clock an internal FSM disclosed later.
[070] It must be noted that command, IV Values are coming from the T_reg register (not shown) and the control signals are T_Reg bits. [071] Giving now a closer look to the internal structure of the analogic block 200 we can make reference to the example of Figure 3 wherein the block 200 embraces a certain number of circuit elements disclosed hereinafter.
[072] Figure 3 is a schematic view of a first embodiment of the hardware block of Figure 2B and according to the present disclosure. In this Figure the depicted current-to -voltage converter is not used during voltage measurement or generation.
[073] The block 200 includes a low voltage detector comprising: a comparator 180 receiving on a voltage input a voltage value to be detected;
- a digital to analog converter 1 10 coupled to a reference voltage potential and having an output connected to other input of said comparator; a Finite State Machine 210 receiving the output of said comparator and producing digital outputs for the inputs of said memory controller.
[074] The D/A converter 1 10 is coupled to a stable reference voltage potential Vref generated for instance by an analogic bandgap generator and receives a digital input signal Count.
[075] The reference voltage Vref (band gap) is to be considered as an external voltage value. A normal value for a bandgap reference could be about 1.2 Volt even if this value is just indicative. A different stable voltage generator may be used to provide Vref.
[076] The output of the D/A converter 1 10 is an analogic value Vf = Vref * Count and is applied to the non-inverting input (+) of the comparator 180.
[077] The comparator 180 has a second inverting (-) input receiving the voltage value Vx to be measured. The example reported herewith should be considered as a schematic indication that the inverting input of the comparator 180 is connected to a node point or to a terminal of the memory portion or component wherein a voltage potential Vx is applied and such a potential must be measured with great precision obtaining a value not affected by noise.
[078] This basic structure of the comparator 180 and converter 1 10 has been further improved by the association of a Finite State Machine (FSM) 210.
[079] The Finite State Machine 210 is a complex logic portion capable to execute algorithms. In the subsequent part of the present disclosure we will provide an example of an algorithm executed by the Finite State Machine 210.
[080] This Finite State Machine 210 operates according to a clock signal CLK of the memory component and received on one input. The FSM receives also as a further input a Command signal issued by the internal memory controller to execute properly the operation that the internal firmware can require depending on the access phase to the memory array. As an alternative, the command signal may arrive from a host device coupled to the memory component or issued by a controller of the System-on-Chip hosting the embedded memory component
[081] A multiplexer 150 is provided between the Finite State Machine 210 and the digital input of the D/A converter 1 10. A selection signal SEL is produced by the Finite State Machine 210 to drive the multiplexer 150 and select the proper path for the input signal to the output of the multiplexer.
[082] The output of the multiplexer 150 is a Count digital input for the D/A converter 1 10.
[083] This multiplexer 150 receives as a first input a logic value corresponding to a voltage or a current measurement and on a second input the output of the Finite State Machine 210.
[084] The output value of the comparator 180 is applied as a feedback input to the Finite State Machine 210. This output value Vf is outputted when it is greater than a voltage value Vx to be measured.
[085] In other words, the output value Vf of the comparator 180 is triggered when the voltage value Vf is greater than the voltage value Vx to be measured. A current- to-voltage converter 130 is depicted also in Figure 3, however it is not used during voltage detection and measurement nor during reference voltage generation. Converter 130 and its functionality will be described below with reference to current detection and measurement and reference current generation.
[086] Moreover, if the measurement is performed for a time interval of a certain duration it is possible to obtain an average value Vx that is less and less affected by possible noise.
[087] In this respect, the Finite State Machine 210 is settable with a programmable Time_out value that represents the max duration of the time interval for performing the measurement of the voltage value Vx.
[088] Just to give an example of a possible algorithm that the Finite State Machine 210 may execute to measure a voltage value Vx, we are reporting hereinafter a list of instructions and parameters that have been adopted for reaching the required measurement.
N = max measures attempt
Wait (TO) u-second (Vx is hopefully a stable value)
Step 1: N++;
The FSM looking for the counter value that provides Vf>Vx Count_H <r counter
Figure imgf000015_0001
counter - 1
Set a Timer DT = T1
do {
/ / Is Vx stable? Is it out of AV? if ((Vrif * CoUnt_H) <Vx | | (Vrif * Count_L) > Vx ) wait (T2) go to step 1 } while ((elapsed time < DT ) | | k>N)
If (k<=N) I Vmeasured [M:0] = [Vrif (Count_H)-Vrif (Count_L)]/2 Else Time_out - 1
[089] It should be noted that the Finite State Machine 210 finds the value in a sequential manner or, as an alternative, in a dichotomic way or with any other method that can speed up the finding of the final value.
[090] As shown in the diagram of Figure 4, during the time interval DT the detected voltage value Vx remains substantially stable within an upper limit Vrif * Count_H and a lower limit Vrif * Count-L. The window delimited by the upper and lower voltage limits of the time interval DT is programmable by the user of the memory component.
[091] Moreover, the FSM 210 is always capable to detect the possible presence of noise since the detected voltage value Vx must remain within the upper and lower limits above reported and when the detected value is outside the expected range, like for instance in the portion of the diagram indicated by the number 190, the measurement is repeated automatically.
[092] Figure 4 is a diagram showing a measure of a voltage value Vx obtained with the block of Figure 3. As shown in the diagram of Figure 4, during the time interval DT the detected voltage value lx remains substantially stable within an upper limit Vrif * Count_H and a lower limit Vrif * Count-L. The window delimited by the upper and lower voltage limits of the time interval DT is programmable by the user of the memory component.
[093] Moreover, the FSM is always capable to detect the possible presence of noise since the detected voltage value Vx must remain within the upper and lower limits above reported and when the detected value is outside the expected range, like for instance in the portion of the diagram indicated by the number 190, the measurement is repeated automatically. [094] The numeric value N represents the maximum number of attempts that the detector should perform for obtaining the required measured value Vx. The other time TO, T1 and T2 are time parameters measured from a common origin
[095] The reported parameters N, TO, Tl , T2 are all programmable in the sense that their value may be set according to the quality and reliability of the measurement to be performed. Even the time interval DT is a parameter that may be programmed.
[096] Just to give an indication of a value assignable to DT it may be set in few tens of milliseconds.
[097] Now, the detector of the present disclosure may be used for measuring also a current value, for instance a current value lx.
[098] Figure 5 is a schematic view of an alternative embodiment of the hardware block of Figure 2B according to the present disclosure and more specifically for current measurements. Several elements in figure 5 are the same as those of figure 3 described above; however, some of them (such as voltage comparator 180) are not used during operation as current detection and measurement and reference current generation as better explained below. The basic portion of the detector disclosed herewith is structured in a similar fashion as the detector described with reference to Figure 3; however, instead of voltage comparator 180 a converter 130 from current to voltage is used.
[099] The structure of this converter 130 is based on a current mirror including a differential cell 140 comprising PMOS and NMOS transistors.
[0100] One input of the current mirror is the current value lx to be measured. In this respect, we must intend that current input terminal of the converter 130 corresponds to a node point or to a terminal of the memory portion or component wherein a current value lx is flowing and such a current value must be measured with great precision obtaining a value not affected by noise. In other words, the current to voltage converter has an input node on a first leg coupled to a node of a circuit in the memory component, the circuit configured to drain the current lx.
[0101] For completeness sake it should be noted that the differential cell 140 of the current mirror includes a first leg associated to the input current value lx and a second leg associated to the output of the D/A converter 1 10.
[0102] More particularly, the output of the D/A converter 1 10 is applied to a gate of an NMOS transistor of the second current mirror leg draining a reference current If. The voltage value Vf at the output of the D/A converter is proportional to the reference voltage Vref (band gap) and is further applied to the gate terminal of a buffer transistor TR having conducting terminal linked between the reference current If node and a ground potential reference. Transistor TR further mirrors the current Iref in the second leg of the current- to-voltage converter 130, making it possibly available at its drain node.
[0103] The output of the voltage or current detector of the present disclosure is represented by a digital output of the FSM wherein a digital value I_Vmeasured [M:0] is presented to the outside world, for instance the SoC controller.
[0104] As previously disclosed with reference to the voltage detector, the Finite State Machine 210 receives as input an output value If outputted by the converter 130 and is capable to issue digital values for the input of the D/A converter 1 10.
[0105] Similarly, to the previous schematic example of Figure 3, the multiplexer 150 receives as input the signal output of the FSM 210 and as a further input a digital current /voltage value I_V_value .
[0106] Similarly, to the example of the voltage detector, it is proposed herewith an algorithm that the Finite State Machine 210 may execute to measure a current value lx. The algorithm includes a list of instructions and parameters that have been adopted for reaching the required measurement.
N = max measures attempt Wait (TO) u- second (lx is hopefully a stable value)
Step 3: N++;
The FSM looking for the counter value that provides If^Ix Count_H <- counter
Figure imgf000019_0001
counter - 1
Set a Timer AT = Tl
do {
/ / Is lx stable? Is it out of IV? if ((Vrif * Count_H * a) <Ix | | (Vrif * Count_L * a) > lx ) wait (T2) go to step 3
} while ((elapsed time < AT ) | | k>N)
If (k<=N) I Vmeasured [M:0] = a * [Vrif (Count_H)-Vrif (Count_L)]/2 Else Time_out <- 1
[0107] As previously disclosed, the numeric value N represents the maximum number of attempts that the detector should perform for obtaining the required measured value lx. The other time TO, T1 and T2 are time parameters measured from a common origin.
[0108] The reported parameters N, TO, Tl, T2 are all programmable in the sense that their value may be set according to the quality and reliability of the measure to be performed. Even the time interval AT is a parameter that may be programmed. [0109] Figure 6 is a diagram showing a measurement of a current value lx obtained with the block of Figure 5. As shown in the diagram of Figure 6, during the time interval DT the detected current value lx remains substantially stable within an upper limit given for instance by Irif*Count_H* a = Vrif*Count_H and a lower limit given by Irif*Count_L* a = Vrif*Count_L. The figure reports a scale factor a (alpha) to allow the proper comparison; a is a conversion factor from voltage to current (e.g., such that Vrif*Count_L*a corresponds to Irif*Count_L and Vrif*Count_H*a corresponds to Irif*Count_H). The window delimited by the upper and lower current limits of the time interval DT is programmable by the user of the memory component.
[0110] Moreover, the FSM is always capable to detect the possible presence of noise since the detected current value lx must remain within the upper and lower limits above reported and when the detected value is outside the expected range, like for instance in the portion of the diagram indicated by the number 290, the measurement is repeated automatically.
[0111] One embodiment of the present disclosure relates to a method to operate a memory device including at least a memory array and a memory controller, the method comprising:
- driving by the memory controller an analogic measurement block through a JTAG interface,
- generating voltage and/or current reference values based on the driving, and;
- detecting that the generated voltage and/or current is correct.
[0112] Figure 7 shows a block diagram of a method 700 according to the present disclosure.
[0113] According to method 700 a memory device including at least a memory array and a memory controller may be operated. [0114] Method 700 comprises, at block 710 driving by the memory controller an analogic measurement block through a JTAG interface. The driving may be carried out according to the embodiments described above with reference to figures 1 to 6. For example, commands may be issued to Finite State Machine 210 by the JTAG interface in controller 3.
[0115] Method 700 comprises, at block 720, generating voltage and/or current reference values based on the driving. The generating voltage and/or current may be implemented by Current/Voltage generation and measurement block 200 described in Figure 2B and in more details 3 and 5, for example.
[0116] Method 700 further comprises, at block 730, detecting that the generated voltage and/or current is correct. Generated voltage or current detection may be implemented by the circuits described in figures 3 and 5, in some embodiments.
[0117] Method 700 may further comprise generating instructions by at least a test register of said JTAG interface for said analogic measurement block. In some embodiments, method 700 may also comprise limiting access to a subset of a plurality of test registers, as described above. In some embodiments, method 700 comprises applying to an input of a comparator a voltage value Vx to be detected and/or applying to an input of a current to voltage converter a current value lx to be detected. Method 700 may also comprise feeding the comparator output and the current to voltage converter output to corresponding inputs of a Finite State Machine and applying digital outputs of said Finite State Machine to a digital to analog converter coupled to a reference voltage potential and having an output connected to another input of said comparator for detecting an average voltage value or an average current value in a time interval
[0118] One of the advantage of the method of the present disclosure is given by the presence of a on board mechanism for measuring voltage values V and current values I related to the flash array without exposing the cells terminal to any contact from an external component, for instance a host device or a SoC to whom the memory is associated. This feature has the great advantage to permit to protect some technological secret not directly measurable from outside the memory component thus rendering the memory device more robust against attacks directed to detect process parameter hacking direct measurement on flash cells.
[0119] In the previous description numerous specific details are discussed to provide a thorough and enabling description for embodiments of the present technology.
[0120] However, one skilled in the relevant art will recognize that the disclosure can be practiced without one or more of the specific details. In other instances, well-known structures or operations often associated with memory devices are not shown, or are not described in detail, to avoid obscuring other aspects of the technology. For example, several functional components of memory devices and/or memory systems that are well-known to those skilled in the art are not discussed in detail below (e.g., circuit components such as multiplexers and decoders, data structures such as address registers and data registers, etc.).
[0121] In general, it should be understood that various other devices, systems, and methods in addition to those specific embodiments disclosed herein may be within the scope of the present technology.

Claims

1. A memory device with analog measurement mode features including:
- at least a memory component with a memory array; a memory controller coupled to the memory component; a JTAG interface in said memory controller; voltage and current reference generators; an analogic measurement block driven by said JTAG interface.
2. The memory device of claim 1 comprising a plurality of test registers in said JTAG interface, each register being associated with a specific address for testing the functionality of the memory component to which the controller is associated.
3. The memory device of claim 1 wherein said JTAG interface includes at least a test register configured to generate instructions for said analogic measurement block.
4. The memory device of claim 1 wherein said voltage and current reference generators are incorporated into said analogic measurement block.
5. The memory device of claim 1 comprising a voltage detector including: a comparator configured to receive on a voltage input a voltage value Vx to be detected;
- a digital to analog converter coupled to a reference voltage potential and having an output connected to other input of said comparator; a Finite State Machine receiving the output of said comparator and configured to produce digital outputs for the inputs of said memory controller.
6. The memory device of claim 5 further comprising a multiplexer between the digital outputs of the Finite State Machine and the inputs of the digital to analog converter.
7. The memory device of claim 6 wherein said Finite State Machine is configured to issue a selection signal for enabling said multiplexer.
8. The memory device of claim 5 wherein the voltage input of the comparator is an inverting input of the comparator.
9. The memory device of claim 5 further comprising a current to voltage converter configured to receive as input a current value lx to be detected and having an output connected to said Finite State Machine.
10. The memory device of claim 9 wherein said current to voltage converter includes a current mirror.
1 1. An apparatus including a host device coupled to a memory component with analog measurement mode features including: at least a memory array in said memory component;
- a memory controller coupled to the memory component; a JTAG interface in said memory controller; voltage and current reference generators; an analogic measurement block driven by said JTAG interface.
12. The apparatus of claim 1 1 comprising a plurality of test registers in said JTAG interface, each register being associated with a specific address for testing the functionality of the memory component to which the controller is associated.
13. The apparatus of claim 1 1 wherein said JTAG interface includes at least a test register configured to generate instructions for said analogic measurement block.
14. The apparatus of claim 1 1 wherein said voltage and current reference generators are incorporated into said analogic measurement block.
15. The apparatus of claim 1 1 wherein said analogic measurement block includes a current detector comprising: a current to voltage converter configured to receive as input a current value lx to be detected and having an output connected to a Finite State Machine;
- a Finite State Machine configured to produce digital outputs for the inputs of said memory controller;
- a digital to analog converter coupled to a reference voltage potential and having an output connected to a transistor of the current to voltage converter.
16. The apparatus of claim 15 further comprising a multiplexer between the digital outputs of the Finite State Machine and the transistor of the current to voltage converter.
17. The apparatus of claim 16 wherein said Finite State Machine is configured to issue a selection signal for enabling said multiplexer.
18. The apparatus of claim 15 wherein the operation of said Finite State Machine is scheduled by a clock signal of the memory component.
19. The apparatus of claim 15 wherein the current to voltage converter has an input node on a first leg coupled to a node of a circuit in the memory component, the circuit in the memory component configured to drain the current lx.
20. The apparatus of claim 15 further comprising a voltage comparator receiving as input a voltage Vx and having an output connected to said finite state machine.
21. A method to operate a memory device including at least a memory array and a memory controller, the method comprising: driving by the memory controller an analogic measurement block through a JTAG interface,
- generating voltage and/or current reference values based on the driving, and; detecting that the generated voltage and/or current is correct.
22. The method of claim 21 further comprising generating instructions by at least a test register of said JTAG interface for said analogic measurement block.
23. The method of claim 21 further comprising limiting access to a subset of a plurality of test registers.
24. The method of claim 21 comprising: applying to an input of a comparator a voltage value Vx to be detected; applying to an input of a current to voltage converter a current value lx to be detected;
- feeding the comparator output and the current to voltage converter output to corresponding inputs of a Finite State Machine; applying digital outputs of said Finite State Machine to a digital to analog converter coupled to a reference voltage potential and having an output connected to another input of said comparator for detecting an average voltage value or an average current value in a time interval.
PCT/IB2019/000479 2019-05-31 2019-05-31 Memory device with analog measurement mode features Ceased WO2020240236A1 (en)

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CN201980096982.XA CN113906514B (en) 2019-05-31 2019-05-31 Memory device with analog measurement mode feature
DE112019007423.7T DE112019007423T5 (en) 2019-05-31 2019-05-31 STORAGE DEVICE WITH ANALOG MEASUREMENT MODE FEATURES
US16/625,371 US11348655B2 (en) 2019-05-31 2019-05-31 Memory device with analog measurement mode features
US17/826,423 US11728002B2 (en) 2019-05-31 2022-05-27 Memory device with analog measurement mode features

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