| 摘要 |
PURPOSE: An apparatus for up-converting a multichannel digital radio frequency is provided to prevent changes of a device value due to temperature changes or secular changes by comprising the device with a digital device having high reliability. CONSTITUTION: A plurality of digital modulators(100) perform digital modulation for a plurality of digital signals. A DAC(300) receives a digital signal from the plurality of digital modulators. The DAC converts the digital signal to a broadband radio frequency signals having respective different frequencies. The digital modulator comprises a receiving part which converts the received digital signal to an I signal and a Q signal and a pulse shaping filter which limits a frequency band of the I signal and the Q signal. The digital modulator comprises a first interpolation part performing the interpolation for the I signal and the Q signal, a numerical control oscillator, and a quadrature modulator which comprises a multiplier and an adder and modulates for the Q signal and the I signal. [Reference numerals] (100) First digital modulator; (200) Second interpolation part; (300) DAC; (AA) First digital signal; (BB) Second digital signal; (CC) n-th digital signal; (DD) Second digital modulator; (EE) n-th digital modulator; (FF) RF |
