A 0.25-μm CMOS OPLL transmitter IC for GSM and DCS applications

A single-chip CMOS global system for mobile communications/digital cellular system dual-band offset phase-locked loop (OPLL) transmitter is presented in this paper. This chip includes a quadrature modulator and an OPLL modulation loop. Except for the loop filter and high-power voltage-controlled oscillator (TX VCO), everything is integrated into this chip to form a dual-band transmitter-This transmitter integrated circuit is fabricated in a 0.25-mum CMOS process. The current consumption without the TX VCO is approximately 23 mA under 2.7-V power supply for both bands. The measured rms and peak phase errors for Gaussian minimum shift-keying (GMSK) modulated signals are approximately 1degrees and 2.4degrees, respectively. The measurements show comparable performance to its BiCMOS counterparts.