Year: 2007
Type: article
Abstract: VCOs are the integral parts of all phase-locked loops, clock recovery circuits and frequency synthesizers. Despite continuous improvements, the design of VCOs remains the main challenge to circuit designers due to very demanding VCO parameters. In a VCO, the frequency of the output signal can be controlled by input control voltage. In most cases, a tuning capacitor is used to tune the output frequency. Ferroelectric capacitors such as BST (barium strontium titanate) continue to find growing demands in high frequency circuits like in VCO for their voltage dependant tunability, high dielectric constant, low noise, low loss and the ease of integration with Si fabrication technology. Detail analysis of various parameters and characteristics of VCO with ferroelectric capacitor is thus needed. Ferroelectric capacitors are nonlinear device, so they produce harmonics. Noise and harmonics are critical parameter for VCO performance. In this research, ferroelectric capacitor tuned VCO has been developed and its non-linearity and harmonics characteristics is investigated and compared with similar VCO built with conventional popular diode varactor. Also a mathematical model to predict harmonic distortion of VCO is presented and its accuracy is verified by comparing computed results with measurement data.
Author: Kabir, Abu T.
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2890135852