Process compensation method for CMOS current controlled ring oscillators

摘要

A current controlled oscillator circuit comprising a "variable- ratio current mirror", for providing a variable output current that varies in response to process. The "variable-ratio current mirror" having a reference MOS transistor and a mirrored MOS transistor, and the reference MOS transistor has a greater predetermined channel length than the channel length of the mirrored MOS transistor. A second current mirror is coupled to the "variable-ratio current mirror" to provide a control current that decreases in response to an increase in the variable output current of the "variable-ratio current mirror." A multi- stage ring oscillator having a plurality of series-connected inverter stages is responsive to the control current of said second current mirror for controlling the frequency of oscillation of said multi-stage ring oscillator.