| 摘要 |
<p>A wireless transmitter includes an RF signal generation circuit, a driver amplifier, and a class-D amplifier. The RF signal generation circuit detects an amplitude signal and a phase signal based on a digital signal subjected to orthogonal modulation, thus generating a pulse phase signal which is High in response to the phase ranging from 0° to 180° but is Low in response to the phase ranging from 180° to 360°. The amplitude signal is subjected to sigma-delta modulation in synchronism with the pulse phase signal and further mixed with the pulse phase signal, thus producing an RF pulse signal. The RF pulse signal is input to the class-D amplifier via the driver amplifier, thus outputting a pulse voltage signal based on a reference voltage which is set in advance. Thus, it is possible to achieve a small-size wireless transmitter with a good noise characteristic and a good distortion characteristic, thus exhibiting high power efficiency.</p> |
