A Study on Active Inductor based VCO to Implement PLL Frequency Synthesizer for Zigbee Standard

This research paper is based on various comparative analysis on precise and wide tuning Voltage Controlled Oscillators (VCO) with minimum phase noise and power consumption, using an active inductor tank circuit for Phase Locked Loop (PLL) based frequency synthesizer to support Zigbee wireless LAN standard, operating on 2.4 GHz ISM band (Industrial, Scientific, Medical), supporting 16 channels of 75MHz bandwidth+5MHz guard-band. The performance of the On-chip passive inductor based LC-VCO (inductive-capacitive) for studying the phase noise characteristics as well the tuning range for locking to the reference signal frequency for supporting Zigbee application has been done. Then it has been compared with the VCO implemented with active inductors based on gyrator technology, as the above technique has certain drawbacks in terms of frequency tuning range, limitation in terms of inductor size and Quality-factor. The analysis has been carried out on 180 nm and 90 nm CMOS technology and simulations carried out in Cadence design environment. In this paper various merits and demerits of the different methods adopted in designing the most critical PLL block, the VCO has been reviewed along with the challenges faced while designing this oscillator block for synthesizer application.