A temperature compensated fully trimmable on-chip IC oscillator

The design of an IC on-chip oscillator including a temperature compensation circuitry, a robust spread reduction technique and digital trimming is described The IC oscillator provides a 12.8 MHz clock signal with a frequency spread of +/-25% before the 8-bits digital trimming. After centering the oscillator at the target frequency, a temperature compensated voltage and current reference circuit allows for less than +/-5% frequency variation when operating from 3 to 5V of power supply and from -40 to 125degreesC of temperature range. The oscillator is implemented in a 0.5 mum CMOS technology, occupies an area of 420x440 mum(2) and dissipates less than 400 muW at 3V of supply without requiring any external reference or components.