Analysis of MOS transformer-coupled oscillators

Techniques for estimating the steady-state voltage amplitudes of MOS transformer-coupled oscillators are presented. A noniterative procedure based on equations and graphical data is used and no simulations are required. By appropriate normalization of variables, the graphical data can be applied to arbitrary transistor sizes and bias conditions. Both single-ended and source-coupled configurations are analyzed. A simple analysis is presented for the squegging phenomenon which exists in single-ended stages. This analysis is used to determine the condition for avoiding squegging. Comparisons are made with SPICE2 simulations and good agreement is achieved over a wide range of operation.