Figure 2
(a) Schematic of the weight shifter with i\(\,\times \,\)j synapse-device array. (b) Theoretical equation of the weight shifter. The conductance value of synapse device (w\(_{ij}\)) can be considered as positively shifted weight value (\(=\)w\(_{ij}^0 +\)w\(_{shift}\)). When we consider that output results of the VMM will be total columnar current (I\(_{array}\)), it is derived from multiplication between input data (V\(_{i}\)) and conductance of synapse device (w\(_{ij}\)). Then, output voltage of one column (V\(_{array}\)) can result from multiplying the I\(_{array}\) by load resistor (R\(_{Load}\)). In the same manner, output voltage of the weight shifter can be derived by multiplying output current of the weight shifter (I\(_{shift}\)) by R\(_{Load}\). As a result, the final output voltage of the VMM (V\(_{output}\)) can be obtained by subtracting the V\(_{shift}\) from V\(_{array}\). (c) Comparison of additionally required devices between conventional pair synapse method and proposed weight shifter for realization of the negative weight. (d) Area ratio (= area of conventional method/area of weight shifter) depending on array size.
