Amard Afzalian

Summary: In this paper, considering the nonlinear effects in two ports consisting of transistor, a general method is proposed for estimating the amplitude of high‐frequency ring oscillators. The proposed method can be generalized to various structures that can be disassembled into similar two ports. Moreover, in each CMOS process, a design procedure can be followed to obtain the desired output power and frequency. This is the first time that the frequency and amplitude of oscillator are related to each other in a system of nonlinear equations. First, considering the maximum achievable oscillation frequency, the analysis of ring oscillator structure is performed for the given output power. The results show that the proposed structure operates at 7 to 18% higher oscillation frequency compared with conventional structures. In the next step, assuming that the oscillator structure and passive network topology are known, another system of nonlinear equations is defined for designing the oscillator for the given frequency and amplitude of oscillation. Finally, the implicit solution, which includes the passive network elements connecting to the transistor, is obtained. The results of equations follow the simulation results with an acceptable error (1% frequency error and about 5% amplitude error).