A 3.2ppm/°C second-order temperature compensated CMOS on-chip oscillator using voltage ratio adjusting technique

A CMOS on-chip oscillator (OCO) for local interconnection network (LIN) bus is presented. The temperature dependence of the output frequency is compensated by the voltage ratio adjusting (VRA) technique. The frequency variation with supply voltage is reduced by a voltage regulator with a wide input range of 1.8 V to 5.0 V. The frequency shift caused by package stress is minimized by resistor placement. Over a temperature range of −40°C to 150°C, the measured temperature coefficients of the output frequency are 3.2ppm/°C without the effect of the package stress and 14.2ppm/°C with that, respectively. The measured frequency variation with supply voltage is within ±0.015%.