This macro-cell is a general purpose, low power internal oscillator core designed for X-FAB 0.35µm XH035 CMOS technology. The circuit has an internal start-up circuit. The CM4013ae requires an external 580nA current bias for proper operation, which can be best achieved using the CM1511ae combo voltage & current reference. A 4-bit digital bus allows frequency calibration against process variations. The core is easily retargeted to any other CMOS technology due to its MOSFET-only oscillator architecture.