Bipolar decoders for nonvolatile memory

Abstract

To program MRAM memory cells current must flow from the memory cell's corresponding bit line to its corresponding word line or from the word line to bit line. To accomplish this, the bit line and word line decoders must be capable of sourcing current (when driving a line positive) and sinking current (when pulling the line negative) to account the memory cell's bipolar nature. Consequently, the decoders must be bipolar. For the negative select switches NMOS devices are used and for the positive select switches PMOS switches are used. To reduce layout area and routing, the negative select switches and positive select switches are separately grouped, with a subset of the positive select switches located between subsets of the negative select switches and vice-versa. The connection for the decoder switches are routed to a central hook-up region for connection to the control lines of the cross-point array.