A 25-ppm/?C, 9-bit linear 11?53 MHz Tunable, 5 ?A/MHz DCO in 90nm for low power microcontrollers

A 9-bit linear VCO based RC oscillator supporting a wide frequency range of 11-53MHz is described. DNL of <; ±0.8 LSB is achieved at 9 bit level of frequency tuning. The oscillator uses chopper stabilization to achieve low drift with temperature variations. The frequency stability is ±25-ppm/°C for the temperature range between -40 to 85 °C in off-chip resistor mode. This oscillator is implemented in 90nm CMOS process technology, occupies 0.1 mm2 area and consumes 5μA/MHz.