CNTFET based Single Ended Fractional Order Colpitts Oscillator: Design,
Simulation and Comparative Analysis
Abstract
In this paper, we design and simulate single ended Colpitts
Oscillator (CO) in integer and fractional order domains. The oscillators
are realized in 32 nm node conventional MOSFET and carbon nanotube field
effect transistors (CNTFET) technologies. Therefore, four COs have been
designed, simulated and rigorously compared. These include integer order
conventional MOSFET based CO, fractional order MOSFET based CO, CNTFET
based integer order CO and CNTFET based fractional order CO, all based
on 32 nm technology nodes. The fractional order approach has been used
as it results in better control over the phase and frequency of the
oscillator. Herein fractional order capacitors of various orders, used
in realizing the fractional order COs, are realized and their frequency
responses are studied. This is being done to ensure whether the designed
pseudo-capacitances have fractional behavior or not in the desired
frequency and phase spectrum. It has been observed that the variation of
fractional order (α) from 0.4 to 0.81 has resulted in a slight reduction
of oscillation frequency from 1.68GHz (α=0.4) to 1.351GHz (α=0.81)
keeping the pseudo-capacitance same at 0.3nF in MOS based topology.
Further, CNTFET based integer order as well as fractional order COs have
been designed to address the power consumption and the complexity issues
of the fractional order COs. The CNTFET based fractional order CO
retains the advantages of fractional order domain as well as power
efficiency of CNTFETs. Furthermore, it has been observed that
integrating fractional order capacitor (FOC) with the CNTFET CO results
in much larger constant phase zone (CPZ), an important performance
measuring parameter. A rigorous comparative analysis of the four COs
designed in this work has been performed.
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