A FM-radio transmitter concept based on an all-digital PLL

A stereo FM-radio transmitter with Radio Data System (RDS) support based on an all-digital PLL is presented. It has been designed as a fully integrated single-chip transmitter in a 90-nm CMOS technology to be compatible with digital deep-submicrometer processes. Target application of the proposed system is the cointegration with baseband processors and transmitters for mobile communication systems. Nowadays mobile phones have a lot of multimedia capabilities e. g. an integrated MP3 player. The proposed transmitter enables a mobile device to stream audio data to a FM receiver which is popular and existing in most households world wide. RDS support allows to send additional information e. g. title and artist of a song. As mobile applications are the main target for the transmitter great attention has been attached to saving power and area. Therefore, the presented transmitter works on a 1 V supply voltage and is aimed for using a 32.768 kHz reference crystal oscillator instead of the commonly used 26 MHz reference oscillator while still providing wideband frequency modulation capability.