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In this paper, we propose a new class-D amplifier with a lower-frequency reference signal by using a spectrum shaping technique, in order to reduce the out-of-band noise, which improves interference problems even when radio equipment is independently designed. The peak-level of the measured out-of-band noise is 15 dB lower than conventional class-D amplifiers. The chip realizes a THD of 0.45% and SNR of 81 dB. The test chip can operate with a single 2 V power supply.