A Low-Power FSK/OOK Transmitter for 915 MHz ISM Band

A PLL-based, low-power, 915 MHz FSK/OOK transmitter is presented. The PLL uses gain-boosted LC VCO and hybrid injection-locked divider topologies to reduce power consumption with acceptable phase noise. In FSK mode, the transmitter consumes 367 mu W from a 1.2 V supply with-18.6 dBm output power and achieves maximum 3 Mbps speed (122.3 pJ/bit). In OOK, power consumption is 314 mu W with maximum 20 Mbps speed (15.7 pJ/bit). The transmitter occupies 0.29 mm(2) of die area in a 130 nm CMOS process.