| 摘要 |
<p>To suppress noise components when digital data is converted to ASK modulated signals to be transmitted over a network. Amplifiers (12,14) produce, based on clocks (CL) generated by a clock generator circuit (10), clocks (CL1) of a relatively small amplitude and clocks (CL2) of a relatively large amplitude, respectively. A switch control circuit (20) generates, based on digital data (D), a control signal (SW) to control switch circuits (16,18). The switch circuits (16,18) selectively pass, in accordance with the signal (SW), either the clocks (CL1) or the clocks (CL2) to an LPF (22). The LPF (22) receives a signal composed of rectangular waves having different amplitudes, and smoothes this signal to produce and output an ASK modulated signal having a continuous sinewave-like waveform.</p> |
