Patent ID: 9692377
Date: 2017-06-27
CPC Classifications: H03F,H04L

Claim:
1. A digital amplitude modulation device comprising: a power amplifier unit including a plurality of power amplifiers connected in parallel to be on/off controlled based on an input sound signal, that amplify power of an input carrier signal when the power amplifiers are an on-controlled state; a combining unit that combines outputs of the power amplifiers in the on-controlled state to output a combined output signal; a filter unit that filters the combined output signal for output as an amplitude modulation signal in an RF band through a signal output terminal; a calculation output unit configured as an analog circuit, that outputs a calculated value based on one of the combined output signal and the amplitude modulation signal; a first protection unit configured as an analog circuit, that outputs, based on the calculated value, a first control signal to place the entire amplifier unit in an off-controlled state; a second protection unit configured as a complex circuit of an analog circuit and a digital circuit, that outputs, based on the calculated value, a second control signal to control an upper limit number of the power amplifiers that can be in the on-controlled state in parallel and a third control signal to on/off control the upper limit number or less or the initial number of the power amplifiers; and a control unit that performs an on/off control of the power amplifiers of the power amplifier unit based on the sound signal, the first control signal, the second control signal, and the third control signal.