A ternary content addressable memory (TCAM) semiconductor device includes a first and second data storage portions each connected to a bit line. The first data storage portion is connected to a first word line, and to a first and third group of in series transistors. The second data storage portion is connected to a second word line, and to a second and fourth group of in series transistors. The first group and second group of in series transistors are each connected to a first match line. The first group is connected to a first search line bar, and the second group is connected to a first search line. A third and fourth group of in series transistors are each connected to a second match line. The third group is connected to a second search line, and the fourth group is connected to a second search line bar.

A logic-memory cell includes a spin-orbit torque device having first, second and third terminals configured such that current between the second and third terminals is capable of changing a resistance between the first and second terminals. In the cell, a first transistor is connected between a logic connection line and the first terminal of the spin-orbit torque device and a second transistor is connected between the logic connection line and the third terminal of the spin-orbit torque device.

Disclosed in the present invention is an ultra-compact CAM array based on a single MTJ and an operating method thereof. The CAM array comprises an M*N CAM core for storing contents, additional reference rows for storing “0” and “1” and reference columns for storing “0” and “1”, a row decoder, a column decoder, transmission gates ENs, write drivers WDs, search current sources I.sub.searchs and two-stage detection amplifiers. The present invention utilizes 1T-1MTJ cells to construct the CAM array, and combines the advantages of the MTJ and CMOS. While ensuring search energy efficiency, a unique structure of the MTJ is utilized to implement a less area overhead and a lower search delay compared with a traditional CMOS-based CAM, and non-volatility is achieved.

Disclosed in the present invention is an ultra-compact CAM array based on a single MTJ and an operating method thereof. The CAM array comprises an M*N CAM core for storing contents, additional reference rows for storing “0” and “1” and reference columns for storing “0” and “1”, a row decoder, a column decoder, transmission gates ENs, write drivers WDs, search current sources I.sub.searchs and two-stage detection amplifiers. The present invention utilizes 1T-1MTJ cells to construct the CAM array, and combines the advantages of the MTJ and CMOS. While ensuring search energy efficiency, a unique structure of the MTJ is utilized to implement a less area overhead and a lower search delay compared with a traditional CMOS-based CAM, and non-volatility is achieved.

A non-volatile programmable circuit configurable to perform logic functions, is provided. The programmable circuit can employ two-terminal non-volatile memory devices to store information, thereby mitigating or avoiding disturbance of programmed data in the absence of external power. Two-terminal resistive switching memory devices having high current on/off ratios and fast switching times can also be employed for high performance, and facilitating a high density array. For look-up table applications, input/output response times can be several nanoseconds or less, facilitating much faster response times than a memory array access for retrieving stored data.

A non-volatile programmable circuit configurable to perform logic functions, is provided. The programmable circuit can employ two-terminal non-volatile memory devices to store information, thereby mitigating or avoiding disturbance of programmed data in the absence of external power. Two-terminal resistive switching memory devices having high current on/off ratios and fast switching times can also be employed for high performance, and facilitating a high density array. For look-up table applications, input/output response times can be several nanoseconds or less, facilitating much faster response times than a memory array access for retrieving stored data.

The disclosure relates in some aspects to on-chip processing circuitry formed within the die of a non-volatile (NVM) array to perform data searches. In some aspects, the die includes components configured to sense wordlines of stored data in the NVM array by applying voltages on the wordlines serially, and then search for an input data pattern within the serially-sensed wordlines. In some examples, the components of the die include latches and circuits configured to perform bitwise latch logic search operations. In other examples, the search components are configured with under-the-array or next-to-the-array dedicated search circuitry that uses registers and/or random access memory (RAM). Other aspects relate to a separate controller device for controlling the on-chip NVM search operations. For example, the controller may determine whether to search for data using search components of the NVM die or processors of the controller based, e.g., on a degree of fragmentation of data.

Ternary content addressable memory (TCAM) circuits are provided herein. In one example implementation, a TCAM circuit can include a first spin-orbit torque (SOT) magnetic tunnel junction (MTJ) element having a pinned layer coupled to a first read transistor controlled by a first search line, and having a spin hall effect (SHE) layer coupled in a first configuration across complemented write inputs. The TCAM circuit can include a second SOT MTJ element having a pinned layer coupled to a second read transistor controlled by a second search line, and having a SHE layer coupled in a second configuration across the complemented write inputs. The TCAM circuit can include a bias transistor configured to provide a bias voltage to drain terminals of the first read transistor and the second read transistor, and a voltage keeper element that couples the drain terminals to a match indicator line.

Ternary content addressable memory (TCAM) circuits are provided herein. In one example implementation, a TCAM circuit can include a first spin-orbit torque (SOT) magnetic tunnel junction (MTJ) element having a pinned layer coupled to a first read transistor controlled by a first search line, and having a spin hall effect (SHE) layer coupled in a first configuration across complemented write inputs. The TCAM circuit can include a second SOT MTJ element having a pinned layer coupled to a second read transistor controlled by a second search line, and having a SHE layer coupled in a second configuration across the complemented write inputs. The TCAM circuit can include a bias transistor configured to provide a bias voltage to drain terminals of the first read transistor and the second read transistor, and a voltage keeper element that couples the drain terminals to a match indicator line.

An apparatus (e.g., a content addressable memory system) can have a controller; a first content addressable memory coupled to the controller and a second content addressable memory coupled to the controller. The controller can be configured to cause the first content addressable memory to compare input data to first data stored in the first content addressable memory and cause the second content addressable memory to compare the input data to second data stored in the second content addressable memory such the input data is compared to the first and second data concurrently and replace a result of the comparison of the input data to the first data with a result of the comparison of the input data to the second data in response to determining that the first data is invalid and that the second data corresponds to the first data.