Mini-FM Transmitter with a Built-in Antenna and a Built-in Storage Battery

摘要

This paper proposes the low-power miniaturized FM transmitter with a built-in antenna for robust short range communications. Recently, short-range wireless communication systems in mobile applications have been researched extensively, and the FM transmitter is one of the most important blocks in the short-range wireless communication systems. The proposed FM transmitter uses FM radio waves to transmit sounds from a mobile system (MP3, PMP, PDA, MP3 Phone et.) to radio or stereo systems within a short distance from the mobile system. The size of the proposed transmitter is 2.6 cm × 2.6 cm × 2.6 cm. The operating voltage of the transmitter is 3.7 V. The proposed system deploys a built-in storage battery and can be operated continuously for 7 hours after fully charging the battery. The transmission frequency of the proposed transmitter is selected as one of three frequencies (88.1 MHz, 88.3 MHz, or 88.5 MHz) depending on utility condition, and the channel separation ability is 40 dB.