# US 2010/0165718 A1 · Apparatus and method for sensing multi-level cell data > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0165718 A1 - Document ID: US20100165718A1 - Status: Published application - Kind: A1 - Application number: 12/436,406 - Filed: 2009-05-06 - Published: 2010-07-01 - Earliest claimed: 2008-12-31 - Assignees: Hynix Semiconductor Inc. - Inventors: Kyoung-Wook Park - Web page: https://patentgrep.com/patent/US20100165718A1 ## CPC - G11C 13/004: {Reading or sensing circuits or methods} - G11C 11/56: using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency - G11C 11/5678: {using amorphous/crystalline phase transition storage elements} - G11C 13/0004: {comprising amorphous/crystalline phase transition cells} - G11C 2013/0054: {Read is performed on a reference element, e.g. cell, and the reference sensed value is used to compare the sensed value of the selected cell} - G11C 2211/5634: Reference cells - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract A multi-level sensing apparatus of the non-volatile memory includes a first sense amplifier configured to compare a first reference voltage with a read data of a bit line and amplify a comparison result to generate a first output; a reference voltage selector configured to select one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output; a second sense amplifier configured to compare the fourth reference voltage with the read data of the bit line and amplify a comparison result to generate a second output; and a decoder configured to decode the first and second outputs to output a sensing data. ## Claims ### Claim 1 A multi-level sensing apparatus of a non-volatile memory, the multi-level sensing apparatus comprising: a first sense amplifier configured to compare a first reference voltage with a read data of a bit line and amplify a comparison result to generate a first output; a reference voltage selector configured to select one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output; a second sense amplifier configured to compare the fourth reference voltage with the read data of the bit line and amplify a comparison result to generate a second output; and a decoder configured to decode the first and second outputs to output a sensing data. ### Claim 2 (depends on 1) The multi-level sensing apparatus of claim 1, wherein the first and second sense amplifiers comprise latch-type differential amplifiers. ### Claim 3 (depends on 1) The multi-level sensing apparatus of claim 1, wherein the second sense amplifier is enabled after the first sense amplifier is enabled. ### Claim 4 (depends on 1) The multi-level sensing apparatus of claim 1, wherein the first sense amplifier maintains the first output until the second sense amplifier generates the second output. ### Claim 5 (depends on 1) The multi-level sensing apparatus of claim 1, wherein a level of the first reference voltage is between a level of the second reference voltage and a level of the third reference voltage. ### Claim 6 (depends on 1) The multi-level sensing apparatus of claim 1, wherein the reference voltage selector comprises: a first switching element configured to selectively provide the second reference voltage; and a second switching element configured to selectively provide the third reference voltage, wherein the first and second switching elements sharing an output terminal are alternatively turned on or turned off by the first output. ### Claim 7 (depends on 6) The multi-level sensing apparatus of claim 6, wherein the first and second switching elements comprise transmission gates. ### Claim 8 (depends on 6) The multi-level sensing apparatus of claim 6, wherein the reference voltage selector further comprises a stabilizing unit configured to precharge the shared output terminal of the first and second switching elements. ### Claim 9 (depends on 6) The multi-level sensing apparatus of claim 6, wherein the reference voltage selector further comprises a stabilizing unit comprising a capacitor for a voltage stabilization of the shared output terminal of the first and second switching elements. ### Claim 10 (depends on 6) The multi-level sensing apparatus of claim 6, wherein the reference voltage selector further comprises a stabilizing unit comprising a precharging unit configured to precharge the shared output terminal of the first and second switching elements, and a capacitor for a voltage stabilization of the shared output terminal of the first and second switching elements, the precharge unit and the capacitor being coupled in parallel to the shared output terminal of the first and second switching elements. ### Claim 11 A multi-level sensing method of a non-volatile memory, the multi-level sensing method comprising: performing a first comparison and amplification operation on a first reference voltage and a read data of a bit line to generate a first output; selecting one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output; performing a second comparison and amplification operation on the fourth reference voltage and the read data of the bit line to generate a second output; and decoding the first and second outputs to output a sensing data. ### Claim 12 (depends on 11) The multi-level sensing method of claim 11, wherein the second comparison and amplification operation is performed after the first comparison and amplification operation. ### Claim 13 (depends on 11) The multi-level sensing method of claim 11, wherein the first output is maintained until the second output is generated. ### Claim 14 (depends on 11) The multi-level sensing method of claim 11, wherein a level of the first reference voltage is between a level of the second reference voltage and a third reference voltage. ### Claim 15 (depends on 11) The multi-level sensing method of claim 11, further comprising precharging an output terminal for the fourth reference voltage before the fourth reference voltage is selected. ### Claim 16 A sensing apparatus of a phase change memory, the sensing apparatus comprising: a data driver configured to be selectively turned on for connection to a bit line of the phase change memory and drive a read data of the bit line in the turned-on state; a first sense amplifier configured to compare the read data transferred through the bit line with a first reference voltage and amplify a comparison result to generate a first output, after the data driver is turned on; a reference voltage selector configured to select one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output; a second sense amplifier configured to compare the sensing voltage, the fourth reference voltage, and the read data of the bit line and amplify a comparison result to generate a second output; and a decoder configured to decode the first and second outputs to output a sensing data. ### Claim 17 (depends on 16) The sensing apparatus of claim 16, wherein the data driver comprises: a bit line selecting unit configured to selectively transfer the read data loaded on the bit line; a bit line driving unit configured to selectively drive a sensing voltage; and a precharging unit disposed between the bit line selecting unit and the bit line driving unit, and configured to precharge an output terminal of the bit line driving unit to the sensing voltage in an interval between the turning-on of the bit line selecting unit and the turning-on of the bit line driving unit. ### Claim 18 (depends on 17) The sensing apparatus of claim 17, wherein the bit line precharging unit comprises; a switching element configured to selectively couple the bit line selecting unit to the bit line driving unit; a precharging element disposed between the switching element and the bit line driving unit, and configured to precharge the output terminal of the bit line driving unit to the sensing voltage in an interval between the turning-on of the bit line selecting unit and the turning-on of the bit line driving unit, wherein the switching element and the precharging element are alternately switched and the switching element is turned on at the same time when the bit line driving unit is turned on. ### Claim 19 (depends on 17) The sensing apparatus of claim 17, wherein the output terminal of the bit line driving unit is coupled to the bit line precharging unit and is shared with input terminals of the first sense amplifier and the second sense amplifier. ### Claim 20 (depends on 16) The sensing apparatus of claim 16, wherein the first and second sense amplifiers comprise latch-type differential amplifiers. ### Claim 21 (depends on 16) The sensing apparatus of claim 16, wherein the second sense amplifier is enabled after the first sense amplifier is enabled. ### Claim 22 (depends on 16) The sensing apparatus of claim 16, wherein the first sense amplifier maintains the first output until the second output of the second sense amplifier is generated. ### Claim 23 (depends on 16) The sensing apparatus of claim 16, wherein a level of the first reference voltage is between a level of the second reference voltage and a level of the third reference voltage. ### Claim 24 (depends on 16) The sensing apparatus of claim 16, wherein the reference voltage selector comprises: a first switching element configured to selectively provide the second reference voltage; and a second switching element configured to selectively provide the third reference voltage, wherein the first and second switching elements sharing an output terminal are alternatively turned on or turned off by the first output. ### Claim 25 (depends on 24) The multi-level sensing apparatus of claim 24, wherein the first and second switching elements comprise transmission gates. ### Claim 26 (depends on 24) The multi-level sensing apparatus of claim 24, wherein the reference voltage selector further comprises a stabilizing unit configured to precharge the shared output terminal of the first and second switching elements. ### Claim 27 (depends on 24) The multi-level sensing apparatus of claim 24, wherein the reference voltage selector further comprises a stabilizing unit comprising a capacitor for a voltage stabilization of the shared output terminal of the first and second switching elements. ### Claim 28 (depends on 24) The multi-level sensing apparatus of claim 24, wherein the reference voltage selector further comprises a stabilizing unit comprising a precharging unit configured to precharge the shared output terminal of the first and second switching elements, and a capacitor for a voltage stabilization of the shared output terminal of the first and second switching elements, which are coupled in parallel to the shared output terminal of the first and second switching elements. ### Claim 29 A sensing method of a phase change memory, the sensing method comprising: selecting and precharging a bit line; driving read data of the bit line after the precharging is completed; enabling a first sense amplifier to performing a comparison and amplification operation on a first reference voltage and the read data of the bit line to generate a first output; selecting one of a second reference voltage and a third reference voltage as a fourth reference voltage according to a logic level of the first output; enabling a second sense amplifier to perform a comparison and amplification operation on the reference voltage and the read data loaded on the bit line to generate a second output; and decoding the first and second outputs to output a sensing data. ### Claim 30 (depends on 29) The sensing method of claim 29, wherein the second sense amplifier is enabled at a time when the first sense amplifier is enabled. ### Claim 31 (depends on 29) The sensing method of claim 29, wherein the first output is maintained until the second output is generated. ### Claim 32 (depends on 29) The sensing method of claim 29, wherein a level of the first reference voltage is between a level of the second reference voltage and a third reference voltage. ### Claim 33 (depends on 29) The sensing method of claim 29, further comprising precharging the output terminal of the fourth reference voltage before the fourth reference voltage is selected.