A three-dimensional (3D) cross-point memory is a solid-state, non-volatile type of memory that for some memory operations requires delivery of accurate currents at many locations around a cross-point memory chip. For example, in one exemplary embodiment of a cross-point memory chip, over 8000 locations on the chip require an accurate low-power current reference that can instantaneously deliver a reference current for a memory operation. Transferring a reference current from a central location to each of a plurality of current mirrors that are highly distributed across a chip has serious drawbacks in both power and chip-area use considerations. Another approach that has been used is to transfer a bias voltage that is remotely converted into a reference current at a plurality of locations. Such an approach presents challenges because each separate current reference source must be calibrated to remove mismatches, such as random device offsets that can appear around a chip that are caused by process offsets. Additionally, the remotely generated reference current is sensitive to bias voltage noise, temperature variations, and supply voltage variations.
It will be appreciated that for simplicity and/or clarity of illustration, elements depicted in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. The scaling of the figures does not represent precise dimensions and/or dimensional ratios of the various elements depicted herein. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements.
USPTO Backgrounds
USPTO Backgrounds