A new triple-controlled type frequency synthesizer using simplified DDFS-driven digital hybrid PLL system

Abstract

It is very important for the triple-controlled type frequency synthesizer to have fast switching speed, stable operation, low power consumption and wide bandwidth. For this goal, a new design method for triple-controlled type frequency synthesizer using the simplified DDFS-driven digital hybrid PLL synthesizer is presented. The simplified DDFS (direct digital frequency synthesizer) is used for the high frequency resolution, circuit simplicity, low power and high-speed switching. The digital hybrid PLL (phase locked loop) provides performance improvements such as high-speed switching, stable operation and high frequency applications. The proposed PLL synthesizer part has a hybrid structure and uses a composite signal of both the D/A converter output and the loop filter output to drive the VCO (voltage controlled oscillator), which makes the PLL frequency synthesizer operate in ultra-fast switching speed. Simulation results show the performance improvements of this synthesizer, as compared with the conventional PLL and stability is verified. Three frequency control parameters are properly used to operate the frequency synthesizer in various electronic applications. The method and results of frequency control parameter assignment are shown for several applications such as GSM, IMT-2000, Bluetooth and PCS system.