Self-Shielded Quad-Band EGPRS Transceiver With Spur Avoidance

The next generation of global system for mobile communications/EDGE large signal polar modulation transceivers from RF micro devices (RFMD), Greensboro, NC, is described. The transceiver is realized as a single die in 0.18-mum CMOS. A very low intermediate frequency receiver architecture at 175 kHz is implemented with automatic image calibration. A novel fractional-N offset phase-locked loop with digital automatic frequency correction allows wider bandwidth operation, as well as the ability to change the IF to avoid channel-dependent spurious responses. An AM loop is added to reduce variations in total radiated power, as well as to limit power amplifier current and voltage. The solution is realized as two self-shielded modules using conformal shielding. Only one additional external capacitor is required to realize the entire radio from the DigRF interface to the antenna.