Signal-controlled ring oscillator with delay cells having constant gain with change in frequency

摘要

A ring-type oscillator with a plurality of delay cells including differential pairs of MOS transistors. Current sources supply current to each pair, and the magnitude of the current supplied is variable by a control voltage to alter the delay of the MOS devices, thereby to alter the frequency of oscillation. Each delay cell MOS device is connected in series with another MOS device biased into its linear region to act as a load resistance. This load is variable by the control voltage so as to tend to maintain the gain of the delay cells constant with changes in frequency of oscillation.