Linearity of bulk-controlled inverter ring VCO in weak and strong inversion
Frequency modulation in ring VCOs is investigated. Primarily, the linearity of conversion from input voltage to output frequency is considered. Bulk-voltage control of the threshold voltage of the VCO transistors is found to be a very promising approach for applications in frequency /spl Delta//spl Sigma/ converters. Different approaches apply in presence of high supply voltages, when transistors