Patent ID: 8981851
Filing Date: 2015-03-17
Classification: H02M,H03F,H03K

Abstract:
1. A power supply modulator comprising: a power amplifier for amplifying a radio signal; a linear amplifier to which negative feedback is applied and receiving an envelope signal of the radio signal; and a pulse current modulator connected to a power supply terminal of the power amplifier via an inductor and connected to an output terminal of the linear amplifier, and outputting a pulse current according to a control signal generated from the envelope signal of the radio signal, wherein the pulse current modulator comprises: a DC current source; a diode having an anode connected to an output terminal of the DC current source and a cathode connected to an output terminal of the pulse current modulator; and a switching element disposed between the output terminal of the DC current source and a ground potential, and controlled by the control signal, wherein the pulse current modulator comprises N (N is an integer equal to or greater than 2) sets of the DC current source, the diode, and the switching element, a current value output from the DC current source in a k (k is an integer ranging from 2 to N)-th set is twice as large as a current value output from the DC current source in a (k−1)-th set, and each of the N sets of switching elements is controlled according to each bit of the control signal which is an N-bit digital signal.