Design And Development Of A 3.6 GHz Dielectric Resonator Oscillator With Wide Tuning Sensivity
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Date
2011-09
Authors
Muhammad Afifi, Amir Effendy
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
An oscillator is required as a second stage LO in a superheterodyne SA. The
oscillator operating frequency is a fixed 3.6 GHz, which is at the lower end of the
microwave frequency range. There are several options of active devices and
resonators that can be considered for the oscillator. A bipolar junction transistor
(BJT) is chosen for the amplifier block due to its low flicker noise corner frequency
and a dielectric resonator (DR) is chosen for its high Q factor. This combination
yields a low phase noise oscillator. Apart from its high Q factor, a DR is a high
dielectric constant ceramic thus enabling a miniaturized microwave oscillator design
compared to a cavity resonator. A varactor-tuned technique is adopted because it
results in a simple planar circuit design compared to optically and magnetically tune
DR.
This dielectric resonator oscillator (DRO) must have very high frequency accuracy.
The SA is specified to operate from 0C to 55C, thus among the design requirement
for the DRO is to be operable in a wide temperature range and, to last for many,
many years. Hence the DRO is controlled by a phase-locked loop (PLL). As the
DRO signal drifts with temperature as well as due to aging, a wide tuning range is
necessary to guarantee a reliable and repeatable performance over its operating life.
An existing DRO with a tuning range of 0.14% at of 3.6 GHz was used as a
benchmark. The development of the new DRO began with investigation on several
proposed varactor-tuned DR resonant structures. The resonant structures were
observed for the resonant frequency tuning range, the linearity of resonant
frequencies versus tuning voltages and the tuning sensitivity. The promising DR
resonant structures – with wide tuning range, linear response and high tuning
sensitivity, were further analyzed to understand the resonant structures coupling
mechanism as well as the potential effect on the DRO performance like phase noise.
Description
Keywords
Design and development of a 3.6 GHz , dielectric resonator oscillator