A temperature insensitive ring oscillator for low power RF communications

CMOS Ring oscillators can be used in RF communication with lower power consumption and smaller area as compared with LC tanks, but they are sensitive to environmental temperatures. It is therefore important to compensate the temperature effect for CMOS ring oscillators. In this paper we studied a new kind of circuit structure. It can make the output frequency of the ring oscillator remain constant at different temperatures. The circuit has been implemented in a 0.35μm COMS technology. The circuit includes three blocks: the temperature sensor block, the temperature adaptive block and the subtraction circuit block. We show theoretical analysis of the principals of the compensation effect. The modeling and parameters tuning process are quite simple. The proposed circuit structure can compensate the temperature effect and stabilize the output frequency of ring oscillators.