Computing in memory electronic device capable of supporting current based analog multiply-accumulation operations and time based analog-to-digital conversion
View Patent ↗Embodiments of the present disclosure described herein relate to a computing in memory electronic device that supports current based analog operations and time based analog-to-digital conversion.
1. An electronic device comprising:
a memory cell array including a plurality of memory cells configured to perform a product operation of an input signal applied through a plurality of operation word lines and a pre-stored weight and to output a first output signal according to the product operation to a plurality of operation bit lines;
a dummy cell array including a plurality of dummy cells configured to generate a reference signal and to output the reference signal to a plurality of dummy bit lines;
a plurality of VTC(Voltage-to-Time Converter) circuits configured to receive a second output signal obtained by summing the first output signal through the plurality of operation bit lines and the reference signal and to convert the second output signal and the reference signal into a time domain; and
a plurality of TDC(Time-to-Digital Converter) circuits configured to compare the converted second output signal with the converted reference signal and to convert the converted second output signal into a digital domain based on a result of the comparison.
2. The electronic device of claim 1 , wherein the plurality of operation bit lines are charged with a preset charging voltage through a precharging circuit, have a voltage reduced than the preset charging voltage when the input signal is the same as the pre-stored weight, and maintain the preset charging voltage when the input signal is different from the pre-stored weight.
3. The electronic device of claim 1 , wherein a pulse width of the input signal is set to be less than or equal to a preset width to maintain a linearity of the second output signal.
4. The electronic device of claim 1 , wherein each of the plurality of VTC circuits includes:
a pull-down circuit configured to generate a pull-down current and to discharge the second output signal and the reference signal based on the pull-down current; and
a conversion circuit configured to output a signal corresponding to logic ‘0’ when voltages of the second output signal and the reference signal exceed a threshold voltage, and configured to output a signal corresponding to logic ‘1’ when the voltages of the second output signal and the reference signal are equal to or less than the threshold voltage.
5. The electronic device of claim 4 , wherein each of the plurality of VTC circuits is configured to discharge the second output signal to a voltage of the same level.
6. The electronic device of claim 1 , wherein each of the plurality of dummy cells stores a dummy weight corresponding to logic ‘0’ or logic ‘1’.
7. The electronic device of claim 6 , wherein the plurality of dummy cells are defined as a plurality of dummy columns connected to each of the plurality of dummy bit lines; and
the reference signal is generated for each of the plurality of dummy columns, and is generated to have an earlier phase in the time domain, as the number of logic ‘1’ increases among the dummy weights stored in each of the plurality of dummy columns.
8. The electronic device of claim 1 , wherein each of the plurality of TDC circuits converts the converted second output signal into logic ‘0’ when a phase of the converted second output signal is later than that of the converted reference signal, and converts the converted second output signal into logic ‘1’ when the phase of the converted second output signal is earlier than that of the converted reference signal.
9. An electronic device comprising:
a control circuit configured to generate a first enable signal, a second enable signal, and a dummy word line signal;
a driver circuit configured to generate an input signal based on the first enable signal and to transfer the input signal to a plurality of operation word lines;
a memory cell array configured to perform a product operation of the input signal and a pre-stored weight and to output a first output signal according to the product operation to a plurality of operation bit lines;
a dummy cell array configured to generate a reference signal based on the dummy word line signal and to output the reference signal to a plurality of dummy bit lines;
a VTC(Voltage-to-Time Converter) array configured to receive a second output signal obtained by summing the first output signal through the plurality of operation bit lines and the reference signal and to convert the second output signal and the reference signal into a time domain; and
a TDC(Time-to-Digital Converter) array configured to compare the converted second output signal with the converted reference signal and to convert the converted second output signal into a digital domain based on a result of the comparison.
10. The electronic device of claim 9 , wherein the dummy cell array includes a plurality of dummy cells,
wherein each of the plurality of dummy cells stores a dummy weight corresponding to logic ‘0’ or logic ‘1’,
wherein the plurality of dummy cells are defined as a plurality of dummy columns connected to each of the plurality of dummy bit lines, and
wherein the reference signal is generated for each of the plurality of dummy columns, and is generated to have an earlier phase in the time domain, as the number of logic ‘1’ increases among the dummy weights stored in each of the plurality of dummy columns.