A Power-Efficient Configurable FSK–OOK Transmitter with Scalable Data Rate for Wireless Medical Applications

Abstract

This paper presents a 922 MHz power-efficient configurable frequency-shift keying–on–off keying (FSK–OOK) phase-locked loop (PLL)-based transmitter. The proposed transmitter works as a multimode structure with configurable data rate and output power. In OOK modulation, by duty cycle adjustment of input data and producing return-to-zero data (RZ-data) by a simple circuit, the data rate can be scaled with power consumption. This implies that any desired level of output power can be transmitted with different power consumption according to the power budget. The transmitter benefits from a new phase frequency detector, an improved charge pump and a low-power voltage-controlled oscillator. The proposed structure represents data rate of 0.24–2.4 Mb/s in OOK mode and 1.8 Mb/s in FSK mode, and it can deliver output power level from − 19.71 to 0.53 dBm. The efficiency of the transmitter at RZ–OOK modulation with data rate of 2.4 Mb/s and output power of 0.53 dBm is 57.25%. Also, the efficiency of transmitter in FSK modulation is 22.1%. The post-layout simulation results in 0.18 µm RF CMOS process are obtained and verify the effectiveness of the proposed circuit.