A 2.5 ppm/°C 1.05-MHz Relaxation Oscillator With Dynamic Frequency-Error Compensation and Fast Start-Up Time

Abstract

This paper presents a 1.05 MHz, on-chip RC relaxation oscillator (ROSC) with a temperature coefficient (TC) of 2.5 ppm/°C and an absolute variation of 100 ppm over the body-compatible range of 0-40°C. The TC increases to 4.3 ppm/°C over the range from -15 °C 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.