Power efficient read circuit for a serial output memory device and method
View Patent ↗An integrated circuit memory device has a plurality of memory cells arranged in a plurality of arrays. Each array has a plurality of rows, and a plurality of column lines, and a plurality of row lines connecting to the memory cells in each array. The memory cell in an array is addressable by a column line and a row line. A column address decoder receives a column address signal and selects one or more column lines of each array in response. A row address decoder receives a row address signal and selects a row line of each array in response. The memory device also has a plurality (k) of sense amplifiers, with one sense amplifier associated with each array, connectable to one or more column lines of the array and receives a signal therefrom supplied from an addressed memory cell. The memory device further has a register; and a control circuit. The control circuit receives a read command, and a clock signal, and in response to the read command activates a first plurality (j) of the plurality (k) of sense amplifiers (j<k) for a time period sufficient to sense the signal on a connected column line associated with each of the plurality (j) of sense amplifiers. The control circuit latches the signal into the register; and deactivates the first plurality (j) of sense amplifiers; and serially outputs the signal from the register in response to the clock signal.
1. A memory device comprising:
a plurality of memory cells arranged in a plurality of arrays, each array having a plurality of rows, and a plurality of column lines, and a plurality of row lines connecting to the memory cells in each array, wherein each memory cell in an array is addressable by a column line and a row line;
a column address decoder for receiving a column address signal and for selecting one or more column lines of each array;
a row address decoder for receiving a row address signal and for selecting a row line of each array;
a plurality (k) of sense amplifiers, one sense amplifier associated with each array, connectable to one or more column lines of said array and for receiving a signal therefrom supplied from an addressed memory cell;
a register; and
a control circuit for receiving a read command, and a clock signal, and in response to the read command for determining a time period sufficient to sense the signal on a connected column line associated with each of a first plurality (j) of said plurality (k) of sense amplifiers (j<k); and for activating said first plurality (j) of sense amplifiers for said time period; and for latching the signal into said register; and for deactivating said first plurality (j) of sense amplifiers; and for serially outputting the signal from said register in response to said clock signal.
2. The device of claim 1 wherein said time period is m cycles of said clock signal.
3. The device of claim 2 wherein said control circuit further activates a second plurality (j) of said plurality (k) of sense amplifiers (j<k) for said time period simultaneously with said serially outputting the signal from said register in response to said clock signal.
4. The memory device of claim 2 wherein each of said memory cells is a split gate floating gate non-volatile memory cell having a first region in a semiconductor substrate, a second region in said semiconductor substrate spaced apart from said first region by a channel region; a floating gate for controlling the conduction of current in a first portion of said channel region; a control gate for controlling the conduction of current in a second portion of said channel region; wherein said control gate is separated from said floating gate by an insulator permitting the Fowler Nordheim tunneling of electrons from said floating gate to said control gate.
5. The memory device of claim 2 wherein each of said memory cells is a stacked gate floating gate non-volatile memory cell having a first region in a semiconductor substrate, a second region in said semiconductor substrate spaced apart from said first region by a channel region; a floating gate for controlling the conduction of current in said channel region; a control gate capacitively coupled to said floating gate.
6. A method of managing power in a memory device having a plurality of memory cells arranged in a plurality (k) of arrays, each array having a plurality of rows, and one or more column lines, and a plurality of row lines connecting to the memory cells in each array, wherein each memory cell in an array is addressable by a column line and a row line, a plurality (k) of sense amplifiers, one sense amplifier associated with each array, connectable to one or more column lines of said array and for receiving a signal therefrom supplied from an addressed memory cell; a register; and a control circuit for receiving a read command, and a clock signal, and in response to the read command for controlling said plurality of sense amplifiers and said register; said method comprising:
determining a time period sufficient to sense the signal on a connected column line associated with each of a first plurality (j) of said plurality (k) of sense amplifiers (j<k);
activating said first plurality (j) of sense amplifiers for said time period;
latching the signal into said register;
deactivating said first plurality (j) of sense amplifiers; and
serially outputting the signal from said register in response to said clock signal.
7. The method of claim 6 wherein said time period is m cycles of said clock signal.
8. The method of claim 6 wherein said method further comprising:
activating a second plurality (j) of said plurality (k) of sense amplifiers (k) for said time period simultaneously with said serially outputting the signal from said register in response to said clock signal.