Motorola Corporation

Arm Limited

Michael L Brauer

Gerard Richard Williams

Paul A Reed

Steven C Sullivan

Mark Allen Silla

Arthur R Piejko

John L Duncan

The present invention relates to a memory device and method for reducing leakage current during a power down mode of operation. The memory device comprises a column of memory cells, with each memory cell being arranged to store a data value, and a pair of bit lines coupled to the column of memory cells. Bit line precharge circuitry is provided for precharging the pair of bit lines to a predetermined voltage level during a precharge phase, the pair of bit lines being arranged such that, when a particular memory cell in the column is selected in an evaluate phase following the precharge phase, a relative change in voltage level between the pair of bit lines indicates the data value stored within the selected memory cell. In accordance with the present invention, the memory device further comprises power down control circuitry arranged when the memory device is to enter a power down mode to prevent the bit line precharge circuitry from precharging the pair of bit lines, and selector circuitry arranged when the memory device is to enter the power down mode to ensure that none of the memory cells in the column are selected. It has been found that by taking this approach during the power down mode of operation, a significant reduction in the leakage current is observed.

Reducing leakage current in a memory device

A memory cache (46) has a plurality of tag arrays (20, 22, 24, 26), a plurality of comparators (38, 40, 42, 44), a plurality a data arrays (12, 14, 16, 18), and a plurality of sense amplifiers (48, 50, 52, 54). The memory cache executes a parallel tag and data array access but does not enable any sense amplifier until a comparator indicates a cache hit. Consequently, the memory cache is suitable for use where power consumption and speed are equally important design constraints.

Memory cache with low power consumption and method of operation

A clock signal (202) is received, wherein the rising edge of the clock signal (202) controls an operation of a memory cell (224) of a memory circuit (200). Address information (204) is received and predecoded prior to the rising edge of the clock signal (202) to produce a row select signal (210). A control signal (201), which is received prior to the rising edge of the clock signal, determines whether the operation is a read operation or a write operation. If the operation is a write operation, new data information (218) is received a data delay after the rising edge of the clock signal (202); the row select signal (210) is delayed such that the memory cell (224) is selected at least a data delay after the rising edge of the clock signal (202); and the new data information (218) is written to the memory cell (224).

Method and apparatus for reducing power consumption in memory circuits

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Austin, TX, United States of America

Michael L Brauer