A 2.5 ppm/°C 1.05 MHz Relaxation Oscillator with Dynamic Frequency-Error Compensation and 8 µs Start-up Time

Abstract

This work presents a 1.05 MHz on-chip RC relaxation oscillator (ROSC) design with a temperature coefficient (TC) of 2.5 ppm/°C and an absolute variation of 100 ppm over the body-compatible range of 0 to 40°C (the TC increases to 4.3 ppm/°C over the range from −15 to 55°C). The high temperature stability is achieved using a PTAT current reference and a TC-tunable resistor bank for first-order frequency error compensation along with a digital frequency compensation (DFC) block using a single-bit temperature sensor for second-order compensation. A measured RMS period jitter of 160 ps is achieved with a high-speed comparator. The active power consumption of the ROSC is 69 µW with a 1 V supply, and the leakage power consumption is 110 nW while power-gated. The ROSC achieves a fast startup time of 8 µs by employing a voltage buffer to quickly stabilize the voltage reference.