Abstract: A feedback control circuit of a pulse-frequency modulation (PFM) converter includes a multiplexer circuit and a detection circuit. The multiplexer circuit is arranged to receive a plurality of candidate peak current values, and output one of the plurality of candidate peak current values as a target peak current value according to a selection control signal, wherein a peak current value of an inductor current pulse of the PFM converter is subject to the target peak current value. The detection circuit is arranged to adaptively adjust the selection control signal according to a pulse interval between two successive inductor current pulses of the PFM converter.

Abstract: An all-pass wideband phase shifter is introduced. Series connections in parallel between two 3 dB hybrid couplers include combining two 90-degree phase shifters and two attenuators to form a novel phase shifter framework. Under specific controls of continuous 90-degree phase shifters and attenuators in four quadrants, 360-degree all-pass phase shifting is effected by phase shifting and vector composition.