Implementation of a Wide Band and Low Noise Signal Generator Based on Phase Locked Loop
Loading...
Date
2023
Authors
Mutinda, M. B
Munji, K. M
Nyenge, L. R
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
A signal generator, an essential electronic test instrument
with versatile applications, finds its utility in various fields
such as cellular communications, radar systems, microstrip
antennas, and electronics labs. This research focuses on the
simulation and design of a low-phase noise signal generator
operating in frequency range of 35 MHz to 3 GHz . To
accomplish this, an Atmega 328P microcontroller on an
Arduino board was employed to control the synthesizer
based on the Phase-Locked-Loop (PLL) concept. The
signal generator’s performance was assessed, with particular
emphasis on predicting and analyzing the phase noise
generated by the PLL components. To ensure a robust
system, a third-order loop filter was devised to effectively
suppress spurs. Through simulation using the ADIsimPLL
simulation tool, optimal values for loop bandwidth (10
kHz) and phase margin (45°) were obtained. The chosen
Phase-Locked-Loop chip for this implementation was
the ADF4351, manufactured by Analog Devices. By
conducting transient analysis, the time required for the PLL
system to transition from the minimum to the maximum
output frequency was determined. Furthermore, the
characteristics of the generator’s signal were investigated
in the frequency range of 35-100 MHz using a cathode
ray oscilloscope, and for 101-3000 MHz using a spectrum
analyzer. The phase noise levels were calculated at different
frequencies (35 MHz, 387 MHz, 1 GHz, 2 GHz, and 2.9
GHz) and analyzed at varying offsets (1 kHz, 10 kHz,
100 kHz, and 1 MHz). Comparatively, the experimental
results indicated a higher level of phase noise than what
was obtained through simulation. Notably, as the output
frequency increased, there was a corresponding increase in
the amount of phase noise. The maximum spur observed
occurred at the third harmonic, measuring -18.6 dBc,
while the minimum spur appeared at the fourth harmonic,
measuring -44.5 dBc.
Description
Article
Keywords
Frequency synthesizer, ADF4351, Loop filter, Phase-Locked-Loop, Voltage-controlled oscillator
Citation
Mutinda, M. B., Munji, K. M., & Nyenge, L. R. (2023). Implementation of a Wide Band and Low Noise Signal Generator Based on Phase Locked Loop. African Journal of Pure and Applied Sciences, 4(1), 50-59.