A 9-MHz Temperature Insensitive Hybrid Ring Oscillator for the On-Chip Clock

To make the ring oscillator insensitive to temperature variation, we propose and design two novel hybrid ring oscillators with temperature compensation. It consists of half of the PTAT (Proportional To the Absolute Temperature) delay cell and half of the CTAT (Complementary To Absolute Temperature) delay cell. Compared with the prior works, the proposed hybrid delay cell is very compact and shows superior temperature variation effect. Implemented in 0.13um CMOS process, we get a 9.28MHz frequency with 7.83 ppm/°C over the temperature from -40°C to 125°C. The area is only 0.0014mm2.