Abstract: A level detector (110, 104) and corresponding method detects (602) whether an output signal level of a VCO (102) is within a window bounded by minimum and maximum thresholds. When the output signal level is not within the window, a loop-control element (108) closes (604) an AGC loop of the VCO and controls the gain of the VCO with a gain-control signal that tracks an AGC bias signal. When the output signal level is within the window, the loop-control element opens (606) the AGC loop and controls the gain with a fixed bias signal derived from the AGC bias signal at the time the AGC loop is opened.

Abstract: A level detector (110, 104) and corresponding method detects (602) whether an output signal level of a VCO (102) is within a window bounded by minimum and maximum thresholds. When the output signal level is not within the window, a loop-control element (108) closes (604) an AGC loop of the VCO and controls the gain of the VCO with a gain-control signal that tracks an AGC bias signal. When the output signal level is within the window, the loop-control element opens (606) the AGC loop and controls the gain with a fixed bias signal derived from the AGC bias signal at the time the AGC loop is opened.

Abstract: A rectifier (306) rectifies (402) an output signal of a VCO (302) to produce an envelope signal proportional to an amplitude of the output signal. An integrator (308) integrates (404) the envelope signal to produce a comparison signal, such that, in response to a change in the envelope signal, during a first mode of operation of the VCO, the comparison signal is allowed to change at a first rate, and, during a second mode of operation of the VCO, the comparison signal is allowed to change at a second rate different from the first rate. A comparator (310) compares (406) the comparison signal with a reference signal (316) to produce a bias signal, and controls (408) a gain of the VCO with the bias signal.

Abstract: A rectifier (306) rectifies (402) an output signal of a VCO (302) to produce an envelope signal proportional to an amplitude of the output signal. An integrator (308) integrates (404) the envelope signal to produce a comparison signal, such that, in response to a change in the envelope signal, during a first mode of operation of the VCO, the comparison signal is allowed to change at a first rate, and, during a second mode of operation of the VCO, the comparison signal is allowed to change at a second rate different from the first rate. A comparator (310) compares (406) the comparison signal with a reference signal (316) to produce a bias signal, and controls (408) a gain of the VCO with the bias signal.