Supply voltage and temperature insensitive current reference for the 4 MHz oscillator

This paper presents a 4 MHz current control ring oscillator with a new temperature and supply voltage immune current reference implemented by 0.35nm CMOS technology. Compared to the conventional oscillator with current reference techniques, the proposed approach shows a significant improvement for the sensitivities of temperature and supply voltage. The current reference is designed by combining positive and negative temperature effect circuits, such that it can exempt from the temperature and supply voltage variations. By HSPICE simulation, this new current reference is insensitive to the supply voltage with variations of -0.47%~0.67% over the supply voltage range of 2.97V to 3.63V, and it is also insensitive to the temperature with variation of 366 ppm/°C over the temperature range of -40°C to 100°C. The proposed oscillator frequency is insensitive to the supply voltage with variations of -15%~20% over the supply voltage range of 2.97V to 3.63V, and it is insensitive to temperature with variation of 404 ppm/°C over the temperature range of-40°C to 100°C.