A 0.35/spl mu/ CMOS fractional-N transmitter for 315/433/868/915 MHz ISM applications

A CMOS fractional-N transmitter offers up to 115.2 kbits/s 2-FSK communications in the 315,433,868 and 915 MHz ISM bands. Transmission is done using direct digital modulation of a fully integrated /spl Delta//spl Sigma/ fractional-N PLL frequency synthesizer. The high PLL bandwidth ensures a low-close-in phase noise, enabling narrowband transmission with low adjacent channel power. The 5.4 mm/sup 2/ IC is integrated in a 0.35/spl mu/m CMOS technology and consumes 14mA at 2.7V.