A neural interface for measuring or stimulating brain neural activity, either as a standalone unit or as a part of a larger system of similar neural interfaces. The neural interface includes a bolt-shaped housing having a tool-engaging head and threaded shank with internal circuitry and at least one electrode. In use, the housing is threaded into a cranial bore such that the electrode contacts the outer surface of the meninges. The neural interface circuitry includes an SAR ADC that provides at least rail-to-rail operation to convert received signals from the electrode(s) into digital data that can be modulated and wirelessly transmitted by intra-skin or other suitable communication.