A Wideband Low-Power LC-DCO-Based Complex Dielectric Spectroscopy System in 0.18- $mu ext{m}$ CMOS Academic Article uri icon

abstract

  • © 1963-2012 IEEE. A low-power integrated LC-oscillator-based broadband dielectric spectroscopy (BDS) system is presented. The real relative permittivity ϵr′ is measured as a shift in the oscillator frequency using an on-chip frequency-to-digital converter. The imaginary relative permittivity ϵr′′ increases the losses of the oscillator tank which mandates a higher dc biasing current to preserve the same oscillation amplitude. An amplitude-locked loop is used to fix the amplitude and linearize the relation between the oscillator bias current and ϵr′ ′. The proposed BDS system employs a sensing oscillator and a reference oscillator where correlated double sampling is used to mitigate the impact of flicker noise, temperature variations, and frequency drifts. A prototype is implemented in 0.18- μm CMOS process with a total chip area of 6.24 mm2to operate in 1-6-GHz range using three dual bands LC oscillators. The total power consumption ranges from 10 to 24 mW depending on the operating frequency. The sensor measures complex permittivity within 2% accuracy for the real part ϵr′ and 5% for the imaginary part ϵr′′. The achieved standard deviation in the air is 2.1 ppm for frequency reading and 110 ppm for current reading.

author list (cited authors)

  • Elkholy, M., & Entesari, K.

citation count

  • 9

publication date

  • April 2017