Designing SRCOs by symbolic-behavioral-modeling of unity-gain cells

A high-level design approach for single-resistance- controlled-oscillators (SRCOs) is introduced by applying symbolic analysis to derive behavioral models of unity-gain cells, e.g. current and voltage followers. The followers are designed by using standard CMOS technology of 0.35μm and their behavior is approached by a first-order fully-symbolic expression which is in good agreement to SPICE simulations. First, a SRCO is simulated by Verilog-A by using ideal behavioral models for the followers. Second, the behavioral models are refined by deriving fully-symbolic expressions, in order to get insight on the design trade-offs. Finally, the SRCO is designed at the transistor level by SPICE, where the values of the passive elements are adjusted from the insights gained by the Verilog-A simulations.