A Dual Band CMOS Class F VCO at mmWave Frequencies
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Date
2021-07-29
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Abstract
With growing demand for 5G applications, there is huge amount of interest for communication
systems operating at 5G frequencies. An integral part of these systems is a Voltage Controlled
Oscillator (VCO). RF signals need to be modulated on-to a carrier frequency for wireless communication.
A VCO are used to generate the carrier frequency signal. Communication standards
dictate the Phase Noise requirement of the oscillator based on the number of channels in the band.
Class F VCOs are known to provide 3dB better Phase Noise than traditional Class B VCOs.
Current work explores this benefit at mmWave frequencies. This work proposes a Class F dual
band VCO with active switching capability, centered around the two mmWave bands at 22 and
35GHz. A Class B VCO is also designed for similar frequency bands, to validate the FoM improvement
of a Class F design. Both the VCOs are designed using Global Foundaries 22nm FDSOI
process.
The Class F VCO achieves a tuning range of 22% and 14% in the 22 and 35GHz bands, and
phase noise 1MHz is less than -112dBc/Hz and -103dBc/Hz in the low and high bands, respectively.
The Oscillator consumes 17mW at 0.8V supply. In comparison, the Class B Oscillator
provides FoM of 190dB and 185dB while the Class F design gives FoM less than -192dB and
-190dB in 22 and 35GHz bands respectively, suggesting that the Class F design gives superior
performance.
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Keywords
VCO, TR, Phase Noise, FoM, FDSOI