This macro-cell is a general purpose, ultra low power internal oscillator core designed for LFoundry 0.15µm LF150 CMOS technology STD (Standard) and LP (Low Power) process. The circuit has internal level shifting and a start-up circuit. A 4-bit digital bus allows frequency calibration against process variations. A digital output signal indicating that the oscillator is operating properly is also available. It also includes an internal current bias. The core is easily retargeted to any other CMOS technology due to its MOSFET-only oscillator architecture.