Nonvolatile memory device, storage device including the same, and method of testing nonvolatile memory device
A nonvolatile memory device may include a page buffer, a control signal generator, and a current mirror. The page buffer may be connected to a bitline and may allow a replicated current to flow through a ground terminal in response to a first control signal and a second control signal. The control signal generator may output the first control signal and the second control signal to the page buffer. The current mirror may output, in a virtual cell mode, a control voltage corresponding to a bias current. The control voltage may correspond to the first control signal.
1 . A nonvolatile memory device comprising:
a page buffer connected to a bitline, and configured to allow a replicated current to flow through a ground terminal in response to a first control signal and a second control signal;
a control signal generator configured to output the first control signal and the second control signal to the page buffer; and
a current mirror configured to output a control voltage corresponding to a bias current in a virtual cell mode,
wherein the control voltage corresponds to the first control signal.
2 . The nonvolatile memory device of claim 1 , wherein the page buffer includes:
a first transistor including a source connected to the ground terminal, a drain, and a gate configured to receive the first control signal;
a second transistor including a source connected to the drain of the first transistor, a drain, and a gate configured to receive the second control signal; and
a third transistor including a source connected to the drain of the second transistor, a drain connected to a sensing node, and a gate configured to receive a bitline connection control signal.
3 . The nonvolatile memory device of claim 2 , wherein the page buffer further includes:
a fourth transistor including a source connected to the bitline, a drain connected to the drain of the first transistor, and a gate configured to receive a bitline selection signal.
4 . The nonvolatile memory device of claim 2 , wherein the control signal generator includes:
a switch configured to output the control voltage as the first control signal to the gate of the first transistor in the virtual cell mode; and
a signal generator configured to generate the second control signal such that a voltage of the drain of the first transistor is equal to the control voltage in the virtual cell mode.
5 . The nonvolatile memory device of claim 4 , wherein a difference between a level of the second control signal and a level of the voltage of the drain of the first transistor corresponds to a threshold voltage of the second transistor in the virtual cell mode.
6 . The nonvolatile memory device of claim 4 , wherein the current mirror includes:
a current source configured to output the bias current; and
a diode transistor connected between the current source and the ground terminal, the diode transistor having a gate connected to a drain of the diode transistor, the gate configured to output the control voltage.
7 . The nonvolatile memory device of claim 2 , wherein the control signal generator includes:
a bitline shielding control signal generator configured to generate a bitline shielding control signal;
a bitline shut-off control signal generator configured to generate a bitline shut-off control signal;
a first switch configured to output, as the first control signal, one of the control voltage and the bitline shielding control signal; and
a second switch configured to output, as the second control signal, one of the bitline shielding control signal and the bitline shut-off control signal.
8 . The nonvolatile memory device of claim 7 , wherein the current mirror is configured to force the bias current from an internal circuit of the nonvolatile memory device.
9 . The nonvolatile memory device of claim 7 , wherein the current mirror is configured to force the bias current from a pad connected to an external device.
10 . The nonvolatile memory device of claim 7 , wherein the current mirror includes:
a comparator configured to compare a voltage of a first node connected to the first switch with a voltage of a second node;
a fourth transistor including a drain connected to a pad and the first node, a source connected to the ground terminal, and a gate connected to the first node;
a fifth transistor including a drain connected to a current source, a source connected to the ground terminal, and a gate configured to receive an output voltage of the comparator;
a sixth transistor including a source connected to a power terminal, a drain connected to the second node, and a gate configured to output a bitline shut-off input signal to the bitline shut-off control signal generator and connected to the drain of the fifth transistor; and
a seventh transistor including a drain connected to the second node, a source connected to the ground terminal, and a gate connected to the first node.
11 . A storage device comprising:
a nonvolatile memory package including at least one nonvolatile memory device; and
a controller configured to control the nonvolatile memory package,
wherein the at least one nonvolatile memory device includes a plurality of page buffers connected to a memory cell array through a plurality of bitlines, and
wherein the at least one nonvolatile memory device is configured to allow, in a virtual cell mode, a replicated current flowing through each of the plurality of page buffers by using a current mirror connected to a pad, and
wherein the replicated current corresponds to a cell current of each memory cell in the memory cell array flowing through each of the plurality of bitlines.
12 . The storage device of claim 11 , wherein the at least one nonvolatile memory device is configured to replicate, in the virtual cell mode, a subthreshold current to a first control transistor of each of the plurality of page buffers.
13 . The storage device of claim 12 , wherein the current mirror is configured to output a gate voltage to a gate of the first control transistor.
14 . The storage device of claim 13 , wherein a drain of the first control transistor is configured to be indirectly biased using a control voltage corresponding to the replicated current.
15 . The storage device of claim 14 , wherein each of the plurality of page buffers further includes:
a second control transistor including a gate configured to receive, in the virtual cell mode, the control voltage such that the biasing of the drain of the first control transistor is adjusted.
16 . A method of testing a nonvolatile memory device including a memory cell array connected to a page buffer through a bitline, the method comprising:
electrically connecting, in a virtual cell mode, a current mirror bias to a gate of a first control transistor of the page buffer; and
applying a test signal, corresponding to the current mirror bias, to a gate of a second control transistor of the page buffer so as to bias a drain of the first control transistor.
17 . The method of claim 16 , further comprising:
receiving a bias current, corresponding to the current mirror bias, from a pad connected to an external device.
18 . The method of claim 16 , further comprising:
generating a bias current, corresponding to the current mirror bias, from an internal circuit of the nonvolatile memory device.
19 . The method of claim 16 , further comprising:
generating the test signal corresponding to the current mirror bias.
20 . The method of claim 16 , further comprising:
in the virtual cell mode, performing a sensing operation corresponding to the bitline,
wherein the performing of the sensing operation is performed without a memory cell of the memory cell array.