Tunable Wideband Microwave Band-Stop and Band-Pass
Filters Using YIG/GGG-GaAs Layer Structures
C.S. Tsai*，G. Qiu*, H. Gao*, G.P. Li*, L.W. Yang**, and S.A. Nikitov***
*Dept. of Electrical Eng. and Computer Science, University of California, Irvine, CA 92697,
cstsai@uci.edu
** Trans RF Corp., Cypress, CA 90630 and Ultra Wideband Inc., Arcadia, CA 91007
***Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow, Center
101999, Russia
ABSTRACT
Tunable wideband microwave band-stop and band-pass
filters using ferromagnetic resonance absorption in yttrium
iron garnet / gadolinium gallium garnet-gallium arsenide
(YIG/GGG-GaAs) layer structures are reported. The
measured characteristics of the band-stop filter shows a
tuning range as large as 2-20 GHz in the resonance
frequency with the corresponding magnetic field tuning
range of 600-5,500 Guass. The peak absorption of 11-37 dB
in the microwave output power has also been measured.
The measured characteristics of the band-pass filters
showing the tunable passband center frequency of 6.90
GHz and 7.90 GHz have been accomplished using the
corresponding two pairs of magnetic fields of 1400 and
1800 Gauss, and 1800 and 2200 Guass, respectively . A
good agreement between the experimental results and the
simulation results based on a lumped-element equivalent
circuit modeling of YIG band-stop filters has been achieved.
Keywords: FMR absorption, YIG filters, tunable band-stop
and band-pass filters.
1
INTRODUCTION
Advanced civilian and military communication and
signal processing systems such as future wideband wireless
communications
and
radars
require
high-speed
electronically-tuned wideband microwave band-stop and
band-pass filters. Ferromagnetic resonance (FMR)-based
microwave devices possess the unique capability of highspeed electronic tunability, using magnetic field, for very
high carrier frequency and very large bandwidth. The group
of bulk crystal YIG-based microwave devices that have
been realized include attenuators, filters, phase shifters,
couplers, delaylines, oscillators etc.. Such bulk crystal YIGbased microwave devices constitute some of the key
components in communication and information processing
systems [1-3]. In recent years, there has been a great deal of
R and D efforts in the realization of ferromagnetic YIGand iron (Fe)-film-based microwave device[4-8]. In this
paper, magnetically-tuned wideband microwave band-stop
filters and band-pass filters on YIG/GGG-GaAs layer
structures are realized. The device configurations, operating
principles, and measured transmission characteristics for
the band-stop filters and the band-pass filters are reported
here. The measured transmission characteristics are found
to be in good agreement with the simulation results based
on the lumped-element equivalent circuit model of YIG
band-stop filters [9]. To the best of our knowledge,
microwave band-pass filters with high-speed tunability in
center frequency and bandwidth have not been reported
heretofore.
2 MAGNETICALLY TUNABLE
MICROWAVE BAND-STOP AND BANDPASS FILTER
A YIG/GGG-GaAs-based tunable band-stop filter is
shown in Fig.1 [5]. The YIG-GGG layer is laid upon the
GaAs-based microstrip line. An incoming microwave
propagating along the microstrip is coupled into the
YIG/GGG layer and maximum coupling and, thus, the peak
absorption of the microwave occurs when its carrier
frequency coincides with the FMR frequency.
Fig. 1. Tunable microwave band-stop filter using
YIG/GGG-GaAs flip-chip configuration
The magnetic field ( H 0 ) dependence of the FMR
frequency ( f r ) is given by:
NSTI-Nanotech 2005, www.nsti.org, ISBN 0-9767985-2-2 Vol. 3, 2005
173
fr (H 0 )
J ª¬ H 0 H an H 0 H an 4 S M s º¼
1/ 2
(1)
where J is the gyromagnetic ratio, 4S M s and H an are,
respectively, the saturation magnetization and the
anisotropy field of the YIG film. Such band-stop filters
have demonstrated a frequency tuning range as large as 2.0
to 20.0 GHz, and a signal absorption level of 11-37 dB at
the FMR frequency (see. Fig. 2).
0
0
4
8
12
16
5500 gauss
-50
4450 gauss
3750 gauss
3150 gauss
-40
2350 gauss
-30
1800 gauss
-20
1100 gauss
600 gauss
Transmission S21(dB)
3 EXPERIMENTAL RESULTS
In the experiments, a 50 : microstrip transmission line
was first fabricated on the 350 P m thick GaAs wafer. A
YIG/GGG sample with the YIG film dimensions of
2
-10
-60
the YIG/GGG layer, as demonstrated in the Fe-GaAs layer
structure-based band-stop filters [10].
20
Frequency (GHz)
Fig.2 Measured transmission characteristics of
YIG/GGG-GaAs-based microwave band-stop filter
a
Clearly, by using a pair of the above band-stop filters in
cascade as depicted in Fig.3 in which separate and different
magnetic field ( H 02 ! H 01 ) are applied, a band-pass filter
with tunable carrier center frequency and bandwidth can be
realized.
2.8 u 9.0mm in the Y and Z directions (see Fig. 1) and 6.8
P m thick was laid upon the GaAs-based microstrip line.
The device including the YIG/GGG sample and the GaAsbased microstrip line are then inserted in a bias magnetic
field facilitated by a pair of permanent magnets.
The measured transmission characteristics of the bandstop filter is shown in Fig.2.
The transmission
characteristics of the band-stop filter versus the carrier
frequency of the incident microwave with a bias magnetic
field as a parameter shows a carrier frequency tuning range
as large as 2 to 20 GHz with the corresponding magnetic
fields tuning range of 600 to 5,500 Guass. Furthermore, the
peak absorption of 11 to 37 dB at the resonance frequencies,
and the out-of-stopband insertion loss of 2.5 dB have been
demonstrated.
The measured characteristics of the band-pass filters
showing the tunable passband center frequency of 6.90
GHz and 7.90 GHz have been accomplished with the
corresponding two pairs of magnetic fields of 1400 and
1800 Gauss, and 1800 and 2200 Guass, respectively. It is
clear that by properly programming the lower and the upper
values of the bias magnetic fields H 01 and H 02 and, thus,
their difference, a passband with scannable center
frequency in a very large frequency range and with large
tunable bandwidth can be accomplished. Finally, both the
out-of-band rejection and the width of the stop-band at the
two end frequencies can be greatly increased using the
microstrip meander line and the nonuniform magnetic field,
respectively.
In conclusion, the tunable wideband microwave bandstop filtes and band-pass filters in cascaded structure using
YIG/GGG-GaAs layer structures have been constructed and
studied. Both types of filters, when fully developed, should
find important applications in wideband real-time RF signal
processing and communication systems.
Fig. 3. A scheme for realization of YIG film-based bandpass filter using a pair of band-stop filters in cascade
Modeling and simulation have been carried out for the
band-stop filters and the cascaded band-pass filters using
the lumped-element equivalent circuit model [9].
Furthermore, the level of absorption in the stopband can be
greatly increased using the microstrip meander line to
facilitate multi-pass coupling between the microwave and
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6.90 GHz
[10] C. S. Tsai, B. S. Chiu, M. J. Chen, C. C. Yu and Y.
Liu., “Wideband tunable high-absorption bandstop
filtering using FMR in Fe-GaAs layer structures,”
Presented at the 9th Joint MMM/Intermag
Conference, Paper AG-05, Jan.5-9, 2004, Anaheim,
CA
7.90 GHz
-10
-30
2
4
6
2200 G
1400 G
-20
1750 G
1800 G
Transmission S21 (dB)
0
8
10
12
Frequency (GHz)
Fig. 4 Measured transmission characteristics of the
YIG/GGG-GaAs-based band-stop filter with tunable center
frequency at 6.90 GHz and 7.90 GHz
REFERENCES
[1] B. Lax and K. J. Button, Microwave Ferrites and
Ferrimagnetics, MiGraw-Hill Book Co., 1962
[2] G. L. Matthaei, “Magnetically Tunable Band-Stop
Filters”, IEEE Trans. on Microwave Theory and
Techniques, Vol.13, 203-212, 1965
[3] J. D. Adam, L.E Davis; G. F. Dionne, E. F.
Schloemann and S. N. Stitzer, “Ferrite Devices and
Materials”, IEEE Trans. on Microwave Theory and
Techniques., Vol.50, 721-737,2002
[4] V. S. Liau, T. Wong, W. Stacey, S. Ali, and E.
Schloemann, “Tunable band-stop filter based on
epitaxial Fe film on GaAs,” in IEEE MTT-S Dig.,
1991,pp. 957-960..
[5] C. S. Tsai and J. Su, “A wideband electronically
tunable magnetostatic wave notch filter in yttrium
iron garnet-gallium arsenide material structure,”
Appl. Phys. Lett., Vol.74, pp. 2079-2080. 1999
[6] C. S. Tsai, J. Su, and C. C. Lee, “Wideband
electronically tunable microwave bandstop filters
using iron film-gallium arsenide waveguide
structures,” IEEE Trans. Magn., Vol.35, 31783180,1999
[7] C. S. Tsai, “Wideband tunable microwave devices
using ferromagnetic film-gallium arsenide material
structures,” J. Magn. Magn. Mater., vol.209, pp. 10–
14, 2000.
[8] N. Cramer, D. Lucic, R. E. Camley, and Z. Celinski,
“High attenuation tunable microwave notch filters
utilizing ferromagnetic resonance,” J.Appl. Phys.,
Vol.87, 6911-6913, 2000
[9] G. Bartolucci, R. Marcelli, “A generalized lumped
element modeling of magnetostatic wave resonators”,
Journal of Applied Physics, Vol.87, pp. 6905-6907,
2000.
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