A Temperature And Process Compensated Ring Oscillator

Oscillator is a kind a circuit that can generate a series of periodic signal through self stimulation. With the development of the integrated circuit and their process, there are a lot of new structures of oscillator, these all supply a precious experience for their development while satisfying the different requirement for the systems. The advantages of the ring oscillator are it is good for designing the high frequency, wide variation and high linear oscillators.Based on the traditional ring oscillator, using the five-stage differential delay cells and the concept of feedback and compensation, a temperature compensated block and a threshold voltage sensing block is designed here. With these blocks, the ring oscillator is designed to satisfy the requirement of compensating temperature and process drifts.The simulation was conducted under a temperature variation from -40℃to 125℃. Five process corners for the design are considered: fast-fast, slow-slow, slow-fast, fast-slow and typical. A B6CA 0.6μm CMOS process model and a 5v supply are adopted during the design. The simulation result shows that the achieved frequency is from 595.0 kHz to702.5 kHz, and the correspondence maximum frequency drifts is not lager than 11% of the output frequency. Therefore, the temperature and process compensated ring oscillator designed here effectively suppressed frequency drifts due to temperature and process variations, in the mean time increase system stability.The ring oscillator is intended to serve as a clock generator or as a part of VCO that to be used in a mix-signal area.