A 99nW 70.4kHz resistive frequency locking on-chip oscillator with 27.4ppm/ºC temperature stability

We present a low power on-chip oscillator for system-on-chip designs. The oscillator introduces a resistive frequency locking loop topology where the equivalent resistance of a switched-capacitor is matched to a temperature-compensated resistor. The approach eliminates the traditional comparator from the oscillation loop, which consumes significant power and limits temperature stability in conventional relaxation oscillators. The oscillator is fabricated in 0.18μm CMOS and exhibits 27.4ppm/^oC and <;7ppm long-term stability while consuming 99.4nW at 70.4 kHz.