Circuits, Systems, and Signal Processing https://doi.org/10.1007/s00034-019-01293-w A Power-Efficient Configurable FSK–OOK Transmitter with Scalable Data Rate for Wireless Medical Applications Tayebeh Azadmousavi 1 · Esmaeil Najafi Aghdam 1 · Javad Frounchi 2 Received: 24 June 2019 / Revised: 15 October 2019 / Accepted: 17 October 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract This paper presents a 922 MHz power-efficient configurable frequency-shift key- ing–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 pro- ducing 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. Keywords Transmitter · PLL · RZ–OOK · Data rate · Low power · Configurable B Tayebeh Azadmousavi ta_azadmousavi@sut.ac.ir Esmaeil Najafi Aghdam Najafiaghdam@sut.ac.ir Javad Frounchi jfrounchi@tabrizu.ac.ir 1 Microelectronic Research Laboratory, Faculty of Electrical Engineering, Sahand University of Technology, Tabriz, Iran 2 Microelectronic and Microsensor Laboratory, University of Tabriz, Tabriz, Iran