Title :
A fractional-N PLL modulator with flexible direct digital phase modulation
Author :
Ferriss, Mark ; Lin, David T. ; Flynn, Michael P.
Author_Institution :
Univ. of Michigan, Ann Arbor, MI, USA
Abstract :
A 2.6 GHz fractional-N synthesizer with a flexible digital modulation scheme is presented. The PLL output is modulated by adding a digital signal directly to the output of the phase detector, in contrast to the typical method of changing the divider ratio. A pre-emphasis filter is used to allow switching rates faster than the loop bandwidth. The transmitter supports GMSK, OQPSK, BSK or any constant envelop modulation scheme. Measurements are presented at 300 kBit/sec. The 0.7 mm2 prototype in 0.13 mum CMOS consumes 20 mA from a 1.5 V supply.
Keywords :
analogue-digital conversion; frequency convertors; modulators; phase locked loops; phase modulation; BSK; CMOS; GMSK; OQPSK; bit rate 300 kbit/s; constant envelop modulation; current 20 mA; flexible direct digital phase modulation; fractional-N PLL modulator; fractional-N synthesizer; frequency 2.6 GHz; phase detector; preemphasis filter; size 0.13 mum; voltage 1.5 V; Bandwidth; Detectors; Digital modulation; Filters; Phase detection; Phase locked loops; Phase modulation; Prototypes; Synthesizers; Transmitters;
Conference_Titel :
Custom Integrated Circuits Conference, 2009. CICC '09. IEEE
Conference_Location :
San Jose, CA
Print_ISBN :
978-1-4244-4071-9
Electronic_ISBN :
978-1-4244-4073-3
DOI :
10.1109/CICC.2009.5280923
