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Research Focus
| Our work in NLD focuses on synchronization phenomena in
arrays of oscillators (injection-locking) and phase-locked loop
circuits, specifically for microwave or RF systems. We have shown
that these systems offer new and interesting methods for achieving
coherence and phase-control for beam-forming in microwave antenna
systems. We have also shown that such arrays can have superior
noise properties, and posses a rich set of dynamics including chaotic
and mode-locking behavior. Currently our interest is in exploring
the applications of such arrays to more sophisticated adaptive beam-forming
systems, and developing improved modeling and design techniques for
practical realization of the arrays. |
Project Descriptions
Evolution of Work at UCSB
| This work was initially undertaken in the context of
spatial power-combining, using a large array of microwave
semiconductor-device oscillators (Gunn, FET, IMPATT, etc.) in an antenna
array, and using the mutual coupling to achieve synchronization and
coherence through injection-locking. In 1993, UCSB graduate
student Peter Liao showed [Liao 1993] that the injection-locking dynamics
could be manipulated for phase-control and beam-scanning, which generated
renewed interest in the work. Subsequently, Jonathan Lynch and Peter
Liao developed improved coupling circuits and dynamical models for these
arrays [Lynch 2000], and these were used in several experimental
demonstrations [Liao 1997,Liao 1998]. Angelos Alexanian extended the
scanning range of the system using a frequency-doubler concept [Alexanian
1997], and visiting scientist Xudong Cao demonstrated a scanning receiver
using a coupled-LO array. Lynch made significant progress in modeling
of arrays for a wide variety of coupling networks, including
mode-locking analysis and demonstrations. Lynch also developed a
coupled phase-locked-loop (PLL) scheme Heng-Chia (Henry) Chang showed that
the phase-noise properties of these arrays scale as 1/N, where N is the
number of oscillators, and demonstrated this experimentally. Henry
also developed an unusual circuit using a low-frequency feedback loop in a
conventional VCO to extend the locking range, exploiting the self-mixing
properties of the oscillator and combining the concepts of phase-locking
and injection-locking. Chang and Shapiro showed that the design of
the oscillators was especially important in realizing certain phase
relationships [Chang 1998]. Paolo Maccarini developed new oscillator
designs specifically for these arrays, and developed a nonlinear test
bench for accurate control and testing of the arrays and verification of
the modeling. |
References
| A selected list of UCSB references. Papers from
1991-2000 are available in a bound reprint volume. Contact Bob York
for a copy. |
- J.J. Lynch, H.C. Chang, and R.A. York,
"Coupled-Oscillator Arrays and Scanning Techniques" in Active
and Quasi-Optical Arrays for Solid-State Power Combining , R.York and Z.
Popovic, eds., Chapter 4, Wiley: New York, 1997.
- R.A. York, "Phase-Locking Dynamics in Active
Integrated Antenna Arrays" Analysis
and Design of Integrated-Circuit Modules, P.S. Hall and
K.C. Gupta, eds., Wiley: New York, 1999.
- R.J. Ram, R. Sporer, H.-R. Blank and R.A. York,
"Chaotic dynamics in coupled microwave oscillators", to appear in
IEEE Transactions on Microwave Theory and Techniques.
- Jonathan J. Lynch and R.A. York, "Synchronization of
Oscillators Coupled through Narrowband Networks", to appear in IEEE
Transactions on Microwave Theory and Techniques.
- T. Heath, K. Wiesenfeld and R.A. York, "Manipulated synchronization:
beam steering in phased arrays", to appear in Chaos, November, 1999.
- H.C. Cheng, A. Borgioli, P. Yeh, R.A. York, "Analysis
of oscillators with external feedback loop for improved locking range and
noise reduction", IEEE Trans. Microwave Theory Tech. , vol. MTT-47,
pp. 1535-1543, August 1999.
- R.J. Pogorzelski, P.F. Maccarini, and R.A. York, "A
continuum model of the dynamics of coupled-oscillator arrays for phase
shifterless beam-scanning", IEEE Trans. Microwave Theory Tech. ,
vol. MTT-47, pp. 463-470, April 1999 and "Correction",
p. 1147, July 1999.
- R.J. Pogorzelski, P.F. Maccarini, and R.A. York, "Continuum
model of the dynamics of externally injection locked coupled oscillator
arrays", IEEE Trans. Microwave Theory Tech. , vol. MTT-47, pp.
471-478, April 1999 and "Correction",
p. 1147, July 1999.
- R.A. York and T. Itoh, "Injection-
and phase-locking techniques for beam control", (Invited Paper),
IEEE Trans. Microwave Theory Tech. , vol. 46, pp. 1920-1929, November 1998.
- H.-C. Chang, X. Cao, M.J. Vaughan, U.K. Mishra and R.A.
York, "Phase noise
in externally injection-locked oscillator arrays", IEEE Trans.
Microwave Theory Tech. , vol. MTT-45, pp. 2035-2042, November 1997.
- H.-C. Chang, E.S. Shapiro, and R.A. York, "Influence
of the oscillator equivalent circuit on the stable modes of parallel-coupled
oscillators", IEEE Trans. Microwave Theory Tech. , vol. MTT-45, pp.
1232-1239, August 1997.
- H.-C. Chang, X. Cao, U.Mishra, and R.A. York, "Phase
noise in coupled oscillators: theory and experiment", IEEE Trans.
Microwave Theory Tech. , vol. MTT-45, pp. 604-615, May 1997.
- J.J. Lynch and R.A. York, "Stability
of mode-locked states of coupled oscillator arrays", IEEE Trans.
Circuits and Systems , IEEE Trans. Circuits and Systems--I. Fundamental
Theory and Applications , vol. 42, pp. 413-418, August 1995.
- J.J. Lynch and R.A. York, "Mode-locked
arrays of coupled phase-locked loops", IEEE Microwave Guided Wave
Lett. , vol. 5, no. 7, pp. 213-215, July 1995.
- J.J. Lynch and R.A. York, "An
analysis of mode-locked arrays of automatic level control oscillators",
IEEE Trans. Circuits and Systems--I. Fundamental Theory and Applictions ,
vol. 41, pp. 859-865, December 1994.
- R.A. York, P. Liao, J.J. Lynch, "Oscillator
array dynamics with broadband N-port coupling networks", IEEE
Trans. Microwave Theory Tech. , vol. MTT-42, pp. 2040-2045, November 1994.
- P. Liao and R.A. York, "A
six-element scanning oscillator array", IEEE Microwave Guided Wave
Lett. , vol. 4, no. 1, pp. 20-22, Jan 1994.
- R.A. York and P. Liao, "A
new phase-shifterless beam-scanning technique using arrays of coupled
oscillators", IEEE Trans. Microwave Theory Tech., special issue on
quasi-optical techniques , vol. MTT-41, pp. 1810-1815, October 1993.
- R.A. York, "Nonlinear
analysis of phase relationships in quasi-optical oscillator arrays",
IEEE Trans. Microwave Theory Tech., special issue on quasi-optical
techniques , vol. MTT-41, pp. 1799-1809, October 1993.
- R.A. York and R.C. Compton, "Measurement
and modeling of radiative coupling in oscillator arrays", IEEE
Trans. Microwave Theory Tech. , vol. MTT-41, pp. 438-444, March 1993.
- R.A. York and R.C. Compton, "Experimental
observation and simulation of mode-locking in coupled-oscillator arrays",
J. Appl. Phys. , vol. 71, no. 6, pp. 2959-2965, 15 March 1992.
- R.A. York and R.C. Compton, "Mode-locked
oscillator arrays", IEEE Microwave Guided Wave Lett. , vol. 1, no.
8, pp. 215-218, Aug 1991.
- R.A. York and R.C. Compton, "Quasi-optical
power-combining using mutually synchronized oscillator arrays",
IEEE Trans. Microwave Theory Tech. , vol. MTT-39, pp. 1000-1009, June 1991.
- A. Alexanian, H.C. Chang and R.A. York, "Enhanced
scanning range in coupled oscillator arrays utilizing frequency
multipliers", 1995 IEEE Antennas and Propagation Society Symposium
Digest (Newport Beach, CA), pp. 1308-1310.
- X. Cao and R.A. York, "Coupled Oscillator Scanning
Technique for Receiver Applications", 1995 IEEE Antennas and
Propagation Society Symposium (Newport Beach, CA), pp. 1311-1314.
- P. Liao and R.A. York, "A high power two-dimensional
coupled oscillator array at X-band", 1995 IEEE MTT-S International
Microwave Symposium (Orlando), pp. 909-912.
- J.J. Lynch and R.A. York, "Pulse power enhancement
using mode-locked arrays of automatic level control oscillators", IEEE
MTT-S International Microwave Symposium (San Diego), pp. 969-972, June 1994.
Related Work
| There is a large body of work on coupled-oscillator systems
in the mathematics, applied physics, and biological sciences. It
would be impossible to list all of them here. Below are some works
by our colleagues, collaborators, or others that have been influential in
our thinking and/or relevant to microwave applications: |
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