THE FREQUENCY TUNING METHOD FOR CONTINUOUS-TIME ANALOG FILTER USING THE SAR SCHEME

摘要

A frequency tuning circuit of a continuous-time analog filter using an SAR(Successive Approximation Register) scheme is provided to complete frequency tuning efficiently in a short time even at a high tuning resolution by generating a tuning code of an integrator used in the frequency tuning circuit by using the SAR scheme. A frequency tuning circuit of a continuous-time analog filter of an active-RC type generates a frequency tuning code by using an SAR(Successive Approximation Register) scheme. A frequency tuning code generator determines a code of each bit in sequence as decreasing binary weight starting from an uppermost bit. The frequency tuning time takes as long as N clock periods.