A 2.4 GHz energy-efficient 18-Mbps FSK transmitter in 0.18 μm CMOS

This paper presents a 2.4 GHz energy-efficient phase-locked loop (PLL)-based transmitter (TX) integrated in 0.18-μm CMOS technology. By using Twin-VCO transmission scheme, the data rate of the transmitter is free of loop bandwidth of PLL with stable carrier frequency. The frequency presetting technique is adopted to not only reduce the lock-in time of the PLL but also minimize the VCO gain (K_VCO) variation. Measured results show that the frequency precision of the Twin-VCO relative to center carrier is less than 21 ppm. The lock-in time of the PLL is less than 7 μs. The TX dissipates 11.6 mW when the output power is 0 dBm at a data rate of 18 Mbps and achieves an energy efficiency less than 0.64 nJ/bit.