An RF CMOS Pulse Modulator for Wireless Communication Polar Transmitters

This letter presents a 3.5-GHz fast-transient CMOS pulse modulator tailored for the application of wireless communication polar transmitters. The techniques of loop matching and shunt <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> desensitization are used to effectuate the modulator’s wideband matching and absorptive characteristics. The measured insertion loss of the modulator is 2.2 dB, and the 3-dB bandwidth is 750 MHz, ranging from 3.03 to 3.78 GHz. The rise time and fall time of the modulated pulses are 0.9 and 0.62 ns, respectively. Tested with a 20-MHz 256-QAM 5G NR signal, the RF polar transmitter using the CMOS modulators can achieve the adjacent channel leakage ratio (ACLR) better than −35 dBc.