RF oscillator based on a passive RC bandpass filter

The purpose of this paper is to design a passive RC bandpass filter (BPF) based voltage-controlled-oscillator (VCO) operating at 2.5 GHz. A preferred type of an oscillator to operate in the GHz frequency range is either an LC oscillator or a ring oscillator.In fabrication,an LC oscillator involving high cost due to the inductors even it exhibits an excellent phase noise performance. On the other hand,ring oscillator resulting a cheap fabrication cost because it can be built with standard CMOS devices. However,it has a poor phase noise and jitter performance and is sensitive to power supply noise. This paper proposes an RC BPF-based oscillator. Its purpose is to close the performance of an LC oscillator than a ring oscillator,as a result to improve the phase noise performance. Furthermore, it can be fabricated in a standard CMOS process since there is no inductor. To prove the proposed concept, a RC BPF-based oscillator was designed with operating frequency of 2.5 GHz and phase noises-98.1 dBc/Hz at 1MHz offset frequency. The power consumption extracted from the simulation is 2.38 mW for 1.8 V supply voltage