Design And Implementation Of PLL-based FSK/GFSK Transmitter

Transmitter is an important part of the wireless system,responsible for sending data between the terminal equipment and the host.With the development of wireless communication technology,more and more requirements on transmitter tend to high performance,low power consumption and low cost.In this thesis,the application background and research status of the PLL-based transmitter are introduced,the implementation method of PLL-based transmitter is summarized.On the basis of this,this thesis designs the transmitter architecture.The transmitter is composed by PLL,voltage storage module and open loop modulator.Among them,PLL is responsible for the generation and calibration of carrier,open loop modulator is in charge of the collection and storage with the VCO control voltage after the PLL calibration is completed.Then,the stored voltage and the baseband signal are encoded to realize the signal modulation.But with the traditional capacitor storage structure the stored voltage will slowly leak in the process of modulation,which will lead to carrier frequency drift.This thesis puts forward a brand-new voltage acquisition storage structure based ADC to solve above problems.Finally,through the simulation illustrates the feasibility of this method.Meanwhile,compared to the traditional voltage storage structure this method has certain performance optimization.The hardware circuit,control program and baseband have been realized,and the system has been tested and validated.The test results show that the transmitter could cover 2400 MHz to 2480 MHz output frequency,support two kinds of modulation signal--FSK and GFSK,support maximum output power of 12.1 dBm,and the modulation data rate can reach 18 Mbps under the premise of FSK error lower than 12%.