A direct conversion WiMAX RF transmitter in 0.18um CMOS technology

This paper describes a direct conversion transmitter for front-end Mobile WiMAX. The transmitter is implemented in 0.18μm CMOS technology and covers the frequency range 2.5-2.7 GHz. The components included in the system are Phase locked loop (PLL), phase frequency detector (PFD), Charge Pump (CP), TSPC based clock divider and Voltage Controlled Oscillator (VCO). On chip CMOS Class-AB Power Amplifier (PA) with adaptive biasing and highly linear active Mixer are also implemented. The transmitter employs fully differential architecture for VCO providing excellent rejection of substrate Noise. The PA has OIP3 in excess of 18 dBm providing EVM <; 3% with 16 QAM modulation scheme and an excellent spectral mask adherence.