Low-power cmos relaxation oscillator design with an on-chip circuit for combined temperature-compensated reference voltage and current generation

Low-power oscillators are essential components of battery-powered medical devices for which the battery life must be maximized, such as pacemakers, blood glucose meters and heart monitors. Energy-efficient oscillators are also needed for devices in radio-frequency identification (RFID) systems and wireless sensor networks. Consequently, the design of reliable low-power oscillators has been a major challenge in many emerging applications in which low-frequency clock signals are generated within single-chip systems. A relaxation oscillator with integrated voltage and current reference generation circuitry is presented in this thesis for on-chip clock signal generation in low-power applications. Designed and simulated in 0.11microm CMOS technology, the oscillator provides a clock signal at a frequency of 20KHz with a temperature coefficient of 314ppm/°C over a range from -20°C to 80°C. The oscillator's output signal frequency has a simulated standard deviation of 7.9% under the influence of device mismatches and process variations. An integrated voltage and current reference generator was developed to provide two reference voltages at 484.6mV and 663.5mV with simulated temperature coefficients of 7.5ppm/ºC and 16ppm/ºC over a range from -20°C to 80°C respectively, as well as a reference current of 26.84nA with a temperature coefficient of 166ppm/ºC over the same temperature range. A prototype chip was fabricated in 0.11microm CMOS process technology with a 1.2V supply. Measurements showed that the oscillator has a power consumption of 4.2microW, a temperature coefficient of 675ppm/ºC, and a phase noise of -105dBc/Hz at 10KHz offset.