A circuit implementing a spiking neural network that includes a learning component that can learn from temporal correlations in the spikes regardless of correlations in the rates. In some embodiments, the learning component comprises a rate-discounting component. In some embodiments, the learning rule computes a rate-normalized covariance (normcov) matrix, detects clusters in this matrix, and sets the synaptic weights according to these clusters. In some embodiments, a synapse with a long-term plasticity rule has an efficacy that is composed by a weight and a fatiguing component. In some embodiments, A Hebbian plasticity component modifies the weight component and a short-term fatigue plasticity component modifies the fatiguing component. The fatigue component increases with increases in the presynaptic spike rate. In some embodiments, the fatigue component increases are implemented in a spike-based manner. In some embodiments, the Hebbian plasticity is a spike-timing-dependent plasticity (STDP), resulting in a fatiguing STDP (FSTDP) synapse.

An embodiment non-volatile memory device includes an array of memory cells in rows and columns; a plurality of local bitlines, the memory cells of each column being coupled to a corresponding local bitline; a plurality of main bitlines, each main bitline being coupleable to a corresponding subset of local bitlines; a plurality of program driver circuits, each having a corresponding output node and injecting a programming current in the corresponding output node, each output node coupleable to a corresponding subset of main bitlines. Each program driver circuit further includes a corresponding limiter circuit that is electrically coupled, for each main bitline of the corresponding subset, to a corresponding sense node whose voltage depends, during writing, on the voltage on the corresponding main bitline. Each limiter circuit turns off the corresponding programming current, in case the voltage on any of the corresponding sense nodes overcomes a reference voltage.

A device includes a non-volatile analog resistive memory cell. The non-volatile analog resistive memory device includes a resistive memory device and a select transistor. The resistive memory device includes a first terminal and a second terminal. The resistive memory device has a tunable conductance. The select transistor is a ferroelectric field-effect transistor (FeFET) device which includes a gate terminal, a source terminal, and a drain terminal. The gate terminal of the FeFET device is connected to a word line. The source terminal of the FeFET device is connected to a source line. The drain terminal of the FeFET device is connected to the first terminal of the resistive memory device. The second terminal of the resistive memory device is connected to a bit line.

A device includes a non-volatile analog resistive memory cell. The non-volatile analog resistive memory device includes a resistive memory device and a select transistor. The resistive memory device includes a first terminal and a second terminal. The resistive memory device has a tunable conductance. The select transistor is a ferroelectric field-effect transistor (FeFET) device which includes a gate terminal, a source terminal, and a drain terminal. The gate terminal of the FeFET device is connected to a word line. The source terminal of the FeFET device is connected to a source line. The drain terminal of the FeFET device is connected to the first terminal of the resistive memory device. The second terminal of the resistive memory device is connected to a bit line.

A filament forming method includes: performing first stage to apply first bias including gate and drain voltages to a resistive memory unit plural times until read current reaches first saturating state, latching read current in first saturating state as saturating read current, determining whether increasing rate of saturating read current is less than first threshold value; when increasing rate of saturating read current is not less than first threshold value, performing second stage to apply second bias, by increasing gate voltage and decreasing drain voltage, to the resistive memory unit plural times until read current reaches second saturating state, latching read current in second saturating state as saturating read current and determining whether increasing rate of saturating read current is less than first threshold value; finishing the method when increasing rate of saturating read current is less than first threshold value and saturating read current reaches target current value.

Provided are a device comprising a bit cell tile including at least two memory cells, each of the at least two memory cells including a resistive memory element, and methods of operating an array of the memory cells, each memory cell including a resistive memory element electrically coupled in series to a corresponding first transistor and to a corresponding second transistor, the first transistor including a first gate coupled to a corresponding one of a plurality of first word lines and the second transistor including a second gate coupled to a corresponding one of a plurality of second word lines, each memory cell coupled between a corresponding one of a plurality of bit lines and a corresponding one of a plurality of source lines. The methods may include applying voltages to the first word line, second word line, source line, and bit line of a memory cell selected for an operation, and resetting the resistive memory element of the memory cell in response to setting the selected bit line to ground.

An embodiment of the invention may include a memory structure. The memory structure may include a first terminal connected to a first contact. The memory structure may include a second terminal connected to a second contact and a third contact. The memory structure may include a multi-level nonvolatile electrochemical cell having a variable resistance channel and a programming gate. The memory structure may include the first contact and second contact connected to the variable resistance channel. The memory structure may include the third contact is connected to the programming gate. This may enable decoupled read-write operations of the device.

Methods, systems, and devices for adjustable programming pulses for a multi-level cell are described. A memory device may modify a characteristic of a programming pulse for an intermediate logic state based on a metric of reliability of associated memory cells. The modified characteristic may increase a read window and reverse a movement of a shifted threshold voltage distribution (e.g., by moving the threshold voltage distribution farther from one or more other voltage distributions). The metric of reliability may be determined by performing test writes may be a quantity of cycles of use for the memory cells, a bit error rate, and/or a quantity of reads of the first state. The information associated with the modified second pulse may be stored in fuses or memory cells, or may be implemented by a memory device controller or circuitry of the memory device.

The gate of the access transistor of a 1 transistor 1 resistor (1T1R) type RRAM cell is biased relative to the source of the access transistor using a current mirror. Under the influence of a voltage applied across the 1T1R cell (e.g., via the bit line), the RRAM memory element switches from a higher resistance to a lower resistance. As the RRAM memory element switches from the higher resistance to the lower resistance, the current through the RRAM cell switches from being substantially determined by the higher resistance of the RRAM device (while the access transistor is operating in the linear region) to being substantially determined by the saturation region operating point of the access transistor.

The gate of the access transistor of a 1 transistor 1 resistor (1T1R) type RRAM cell is biased relative to the source of the access transistor using a current mirror. Under the influence of a voltage applied across the 1T1R cell (e.g., via the bit line), the RRAM memory element switches from a higher resistance to a lower resistance. As the RRAM memory element switches from the higher resistance to the lower resistance, the current through the RRAM cell switches from being substantially determined by the higher resistance of the RRAM device (while the access transistor is operating in the linear region) to being substantially determined by the saturation region operating point of the access transistor.