Superconducting implementation of neural circuits is presented. A neuron element is composed of a coupled-SQUID, which is a combination of a single-junction SQUID and a double-junction SQUID. A synapse element is composed of multiple double-junction SQUIDs. To demonstrate the abilities of these circuits experimentally, a 3-bit neuralbased A/D converter, which contains three neurons and three synapses, has been fabricated using a niobium integration technology. This is the prst successful implementation of both neuron and active synapse elements into a superconducting neural network.