Weight matrix circuit and weight matrix input circuit
Provided are a weight matrix circuit and a weight matrix input circuit. The weight matrix circuit includes a memory array including n input lines, m output lines, and n×m resistive memory devices each connected to the n input lines and the m output lines and each having a non-linear current-voltage characteristic, an input circuit connected to each of the input lines, and an output circuit connected to each of the output lines. The input circuit is connected to the resistive memory devices such that the weight matrix circuit has a linear current-voltage characteristic.
1. A weight matrix circuit comprising:
a memory array configured to include n input lines, m output lines, and nxm resistive memory devices each connected to the n input lines and the m output lines and each having a non-linear current-voltage characteristic;
an input circuit configured to be connected to each of the input lines; and
an output circuit configured to be connected to each of the output lines,
wherein the input circuit is connected to the resistive memory devices such that the weight matrix circuit has a linear current-voltage characteristic, and
wherein the input circuit comprises:
an operational amplifier (OP-amp) having an inverting input electrode, a non-inverting input electrode, and an output electrode;
a resistor connected to the inverting input electrode; and
a resistive memory device having ends which are connected to the inverting input electrode and the output electrode.
2. The weight matrix circuit of claim 1 , wherein the resistive memory devices are any one selected from the group consisting of a resistive random access memory (RRAM), a magnetic random access memory (MRAM), a phase-change random access memory (PCRAM), and a ferroelectric random access memory (FeRAM).
3. The weight matrix circuit of claim 1 , wherein the non-linear current-voltage characteristic of the resistive memory devices is modeled as a hyperbolic sine function (sinhx) with respect to a provided voltage.
4. The weight matrix circuit of claim 1 , wherein the input circuit is modeled as an inverse function of a current-voltage characteristic of the resistive memory devices.
5. A weight matrix input circuit for providing an input to a weight matrix circuit which stores weight values between neurons of a neural network, the weight matrix input circuit comprising:
an operational amplifier (OP-amp) having an inverting input electrode, a non-inverting input electrode, and an output electrode;
a resistor connected to the inverting input electrode; and
a resistive memory device having ends connected to the inverting input electrode and the output electrode,
wherein the weight matrix circuit connected to the weight matrix input circuit has a linear current-voltage characteristic.
6. The weight matrix input circuit of claim 5 , wherein the current-voltage characteristic of the weight matrix circuit is modeled as a hyperbolic sine function, and
a current-voltage characteristic of the weight matrix input circuit is modeled as an inverse function of the hyperbolic sine function.