A 0.18-(mu)m CMOS offset-PLL upconversion modulation loop IC for DCS1800 transmitter

A DCS1800 offset-phase-locked-loop upconversion modulation loop integrated circuit (IC) fabricated in a 0.18-(mu)m CMOS technology is presented in this paper. This IC operates at 2.8-V supply voltage with a current consumption of 36 mA. The measured root-mean-square and peak phase errors of the Gaussian minimum shift keying (GMSK) transmission signal are 1.6(degree) and 4(degree), respectively. It is shown that such circuits can be implemented in CMOS process with current dissipation and performance comparable to BiCMOS chips. Advantages of upconversion modulation loop and design issues of I/Q modulators are also described.