Data mask encoding in data bit inversion scheme

摘要

Devices, circuits, and methods for data mask and data bit inversion encoding and decoding for a memory circuit. According to these methods and circuits, the number of data lines/pins required to encode data mask information and data bit inversion information can be reduced. In an embodiment the data mask and data inversion functions for a portion of data, such as a data word, can be merged onto a common pin/data line. In other embodiments, a data mask instruction can be conveyed through a transmitted data word itself without using any extra pins. According to these embodiments, the pin overhead can be reduced from two pins per byte to one pin per byte.

主权项

1. A memory device comprising:
a memory core; a plurality of data bit input pins; a data bit inversion (DBI) input pin; a decoder configured to receive a data word from the plurality of data bit input pins and a DBI signal from the DBI input pin, and output a decoded data word, wherein the decoded data word is inverted with respect to the received data word when the DBI signal indicates inversion is to be performed and is the same as the received data word when the DBI signal indicates inversion is not to be performed; and data mask code detection logic configured to receive the data word from the plurality of data bit input pins and the DBI signal from the DBI input pin in parallel with the decoder, determine whether the received data word is encoded in a compliant or noncompliant state, and output a data mask signal, wherein the data mask signal has a first state that indicates data masking is to be performed when the received data word is determined to be in a noncompliant state and a second state that indicates data masking is not to be performed when the received data word is determined to be in a compliant state, wherein the determination of whether the received data word is encoded in the compliant or noncompliant state depends at least partially upon the logic state of the DBI signal; wherein the decoded data word is allowed to be written to the memory core when the data mask signal has the second state and is not allowed to be written to the memory core when the data mask signal has the first state.