Fig. 8: Equivalent electrical circuit of the topology used to implement the mathematical difference between two electrical signals.
From: Hardware implementation of memristor-based artificial neural networks
a Assuming that voltage inputs are unipolar (that is, only negative or positive), it is required to first transduce the current signals into voltage and then add an operational amplifier in a subtractor configuration. b If bipolar signals can be applied in the inputs, by biasing the negative synaptic weights with a voltage or opposite polarity, summing the resulting currents in a common node (Kirchhoff’s Law for Current) already solves the subtraction operation, and only one transimpedance amplifier is required per column.
