A implementation of fully integrated frequency synthesizer For ISM band transceiver

A fully integrated frequency synthesizer for ISM band transceiver has to exhibit low phase noise characteristic and small chip size. For the designed frequency synthesizer, the center frequency is 1.2 GHz and linear tuning range of over 450 MHz. To improve the performance of the frequency synthesizer, the phase noise of voltage controlled oscillator is minimized by enhancing Q-factor of the inductor through an inductor design modeling. In addition, an improved charge pump is proposed to minimize non-ideal effect of its performance. The simulation showed the proposed charge pump improved the jitter to 1.5 ns compared with 2.37 ns of the conventional charge pump. The designed circuits have been implemented with 0.18 mum RF CMOS technology.