Ankita Bhatt1,2 and *Sajad A Loan2
1Electronics and Communication Engineering, Birla
Institute of Technology and Science, Pilani India
2Electronics and Communication Engineering, Jamia
Millia Islamia New Delhi, India Corresponding author email:
*sloan@jmi.ac.in
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.
Index Terms : CNTFET, Fractional circuit, Oscillators, SPICE.