Chaotic Regimes in Oscillating Logic Gate Networks

Sereres Johnston

Experimental Setup

• 74AC04 inverters• Tektronix oscilloscope

– 2.5x10^9 samples / second• Xantrex DC power supply

– 0-5V range used• Agilent signal generator

– Microwave frequencies

• Time delay– Lengths of coaxial cable

• Topologies– 1NOT, 1NOT + time delay, 5NOT

• Reduced Loop Gain– Introduction of feedback resistors

• Chaotic data encoding and transmission.– Data coded in chaotic state,

rather than phase or amplitude

• Detectors in the radio-frequency portion of the electromagnetic spectrum.– Advanced intrusion detection

for buildings

• Models for other complex systems– Gene expression– Neural networks

Necessary components:

- Steep transfer curves

- Time delayed feedback

Above: representative transfer curves for analog inverters

Why Chaos? Why Care?

Network Topology

5NOT

1NOT +time delay +injected signal

Time delay, gain reduction

Microwave signal injection

1NOT

3.7 V power supply

3.8 V power supply

Right: contour plot of slope through zero

Signal injected at:• 443 MHz frequency• 50 mV amplitude

Signal injected at:• 443 MHz frequency• 150 mV amplitude

Signal injected at:• 443 MHz frequency• 250 mV amplitude

Signal injected at:• 443 MHz frequency• 350 mV amplitude

Signal injected at:• 443 MHz frequency• 450 mV amplitude

Signal injected at:• 443 MHz frequency• 550 mV amplitude

Signal injected at:• 443 MHz frequency• 650 mV amplitude

Signal injected at:• 443 MHz frequency• 750 mV amplitude

Signal injected at:• 443 MHz frequency• 850 mV amplitude

Signal injected at:• 443 MHz frequency• 900 mV amplitude

Signal injected at:• 443 MHz frequency• 1V amplitude

Signal injected at:• 443 MHz frequency• 1.3V amplitude

AcknowledgmentsMany thanks to John Rodgers and Daniel P. Lathrop for their support and advice through the duration of the program.

I would also like to thank the University of Maryland and the Institute for Research in Electronics and Applied Physics (IREAP) as well as the TREND program.