Patent ID: 8081038
Filing Date: 2011-12-20
Classification: H03K,H03L

Abstract:
1. A ring oscillator comprising: a plurality of delay cells coupled in a loop to generate an oscillation frequency, wherein each delay cell comprises: a transconductance circuit configured to receive first differential input signals from the preceding delay cell, invert the first differential input signals, and output differential output signals, which are delayed by a predetermined time through the inversion, to first and second output nodes; an inversion-rate control circuit connected to the transconductance circuit and configured to vary an inversion rate of the first differential input signals in response to a first control signal provided from an exterior; an active load circuit configured to receive second differential input signals from the delay cell preceding by two stages and provide an active load to the transconductance circuit; and an output-rate control circuit configured to vary an output rate of the differential output signals, which are generated from the transconductance circuit, in response to a second control signal provided from the exterior, wherein the output-rate control circuit comprises: