A 400MHz current starved ring oscillator with temperature and supply voltage insensitivity

A ring oscillator with temperature and supply voltage compensation is presented in this paper. In the proposed configuration, low drop-out regulator (LDO) is adapted to reject the influence of supply voltage variation on the output frequency of ring oscillator. Temperature sensor and voltage adder/subtractor are used to generate a bias voltage which can maintain a constant output frequency of ring oscillator with temperature variation. In addition, for the purpose of high stability, a high accuracy band-gap reference provides DC bias voltage for LDO, temperature sensor and voltage adder/subtractor. The proposed circuit configuration is realized in 0.35 μm CMOS technology and simulated with cadence tools. The simulation results show the temperature coefficient of output frequency is 57.5 ppm/°C in temperature range of -20 to 100°C and the variation of output frequency with supply voltage is ±0.07% in voltage rang of 3.2 to 4 V.