A 250 kHz Resistive Frequency-Locked On-Chip Oscillator with 24.7 ppm/°C Temperature Stability and 2.73 ppm Long-Term Stability

This work presents a resistive frequency-locked loop on-chip oscillator with a double chopper stabilization technique to improve the temperature stability and long-term stability. The negative feedback topology achieves both a low temperature coefficient (TC) and good energy efficiency. A prototype device is fabricated in 0.18-mu m CMOS technology and exhibits a 24.7 ppm/degrees C temperature stability and 2.73 ppm long-term stability while consuming just 293 nW under an oscillation frequency of 250 kHz. The use of the double chopper stabilization technique effectively eliminates the TC-sensitive non-idealities, including the current mismatch and offset voltage of the amplifier. Moreover, the low-frequency flicker noise is also mitigated; resulting in a 16X improvement in the long-term stability.