Ultra low power pulse generator based on a ring oscillator with direct path current avoidance

This paper presents a wide frequency range, ultra low power pulse generator based on a ring oscillator. The proposed architecture avoids the direct path current, reaching pulse frequencies down to the kHz range while maintaining the power consumption proportional to frequency. Furthermore, the used topology for the current starved inverter circuit improves the symmetry between rising and falling edges of the output signals of the ring oscillator with respect to the traditional implementation. A frequency range from 1.75kHz to 10MHz consuming 1nW and 3.6μW respectively was achieved in a 130nm CMOS process. The modular design can be used to generate any non-overlapping pulse sequence with variable width.