Design Of Low Phase Noise Very High Frequency (VHF) Low Band Voltage Controlled Oscillator (VCO) For Transceiver Application
Loading...
Date
2011-09
Authors
Yeap, Kim Huat
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
There is little research in transceiver technology for Very High Frequency (VHF)
low band nowadays because many communication systems today use higher
frequency bands. However, low band is still required in specific fields, such as public
safety due to its extensive and precise coverage. This thesis researches improvement
in the phase noise of the low band Voltage Controlled Oscillator (VCO). As such, the
back-to-back varactor, the linearizing inductor, and the low noise biasing network are
introduced. Sensible placement of the bypass capacitor, choke, and ferrite bead as
well as proper selection of parts have been studied and implemented. The transmitter
VCO design comprises of an oscillator cascaded with a buffer and a pad attenuator to
improve the output matching. The receiver VCO has a similar design but added with
a filter at the output to suppress its harmonics before injected into the mixer.
Momentum co-simulation is introduced and proven as a closer correlated simulation
method compared to conventional simulations. The receiver VCO measured phase
noise is around -126 dBc/Hz at 12.5 kHz offset and around -136 dBc/Hz at 25 kHz
offset. The transmitter VCO measured phase noise is around -134 dBc/Hz at 12.5
kHz offset and around -141 dBc/Hz at 25 kHz offset. Both VCOs phase noise
comply with the specifications of < -118 dBc/Hz at 12.5 kHz offset and < -133
dBc/Hz at 25 kHz offset. Such VCO is suitable in both domestic and public safety
applications.
Description
Keywords
Design of low phase noise very high frequency , low band voltage controlled oscillator