Patent ID: 8433267
Filing Date: 2013-04-30
Classification: H03C,H04L

Abstract:
1. An amplitude modulator comprising: a signal processing section for receiving a source signal for wide bandwidth use, splitting the received source signal into two source signals which are for lower frequency use and for higher frequency use, respectively, signal processing the two source signals individually, and outputting a lower-frequency-use source signal and a higher-frequency-use source signal; a first modulation section for modulating the lower-frequency-use source signal outputted by the signal processing section and outputting a lower-frequency-use modulation signal; a second modulation section for modulating the higher-frequency-use source signal outputted by the signal processing section and outputting a higher-frequency-use modulation signal; and a synthesis output section for inputting the lower-frequency-use modulation signal outputted by the first modulation section to a first input terminal, the input of the lower-frequency-use modulation signal causing extraction of only a lower-frequency component, for inputting the higher-frequency-use modulation signal outputted by the second modulation section to a second input terminal, the input of the higher-frequency-use modulation signal causing extraction of only a higher-frequency component, for synthesizing the higher-frequency component and the lower-frequency component, and for outputting a modulated signal which corresponds to the source signal for wide bandwidth use, to a next step, wherein in the synthesis output section, the first input terminal is a positive side input terminal of an operational amplifier, a resistance is connected in series to an output terminal of the operational amplifier, and a capacitor is connected in parallel with a line in which the resistance is provided, an end of the line is connected to a gate of an output transistor, and serves as the second input terminal, and a source of the output transistor is connected to a negative side input terminal of the operational amplifier, and serves as an output to the next step.