Browsing by Author "Wang, Liquan"
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- DC characterization of tunnel diodes under stable non-oscillatory circuit conditionsPublication . Wang, Liquan; Figueiredo, J. M. L.; Ironside, C. N.; Wasige, EdwardA common problem in designing with Esaki tunneling diodes in circuits is parasitic oscillations, which occur when these devices are biased in their negative differential resistance(NDR) region. Because of this, the measured current–voltage(I–V )characteristics in the NDR region are usually incorrect, with sudden changes in current with voltage and a plateaulike waveform in this region. Using a full nonlinear analysis of the shunt-resistor-stabilized tunnel diode circuit, we have established the criteria for the range of element values that give stable operation. On this basis, I–V measurement circuits can be designedto be free from both low-frequency bias oscillations and highfrequency oscillations. The design equations lead to a direct I–V measurement setup in which the stabilization resistor in series with a capacitor can be employed. Experimental results validate the approach, and this is confirmed by second-derivative analysis (d2I/dV 2) of the measured I–V characteristics.
- A liénard oscillator resonant tunnelling diode-laser diode hybrid integrated circuit: model and experimentPublication . Slight, Thomas James; Romeira, Bruno; Wang, Liquan; Figueiredo, J. M. L.; Wasige, Edward; Ironside, C. N.We report on a hybrid optoelectronic integrated circuit based on a resonant tunnelling diode driving an optical communications laser diode. This circuit can act as a voltage controlled oscillator with optical and electrical outputs. We show that the oscillator operation can be described by Liénard’s equation, a second order nonlinear differential equation, which is a generalization of the Van der Pol equation. This treatment gives considerable insight into the potential of a monolithic version of the circuit for optical communication functions including clock recovery and chaotic source applications.
- Nonlinear dynamics of resonant tunneling optoelectronic circuits for wireless/optical interfacesPublication . Romeira, Bruno; Figueiredo, J. M. L.; Slight, Thomas James; Wang, Liquan; Wasige, Edward; Ironside, C. N.; Kelly, Anthony E.; Green, RichardWe report on experimental and modeling results on the nonlinear dynamics of a resonant-tunneling-diode-based(RTD) optoelectronic circuits that can be used as the basis of a wireless/optical interface for wireless access networks. The RTD-based circuits are optoelectronic integrated circuits that have negative differential resistance and act as optoelectronic voltage-controlled oscillators. These circuits display many of the features of classic nonlinear dynamics, including chaos and synchronization. These highly nonlinear oscillators behaves as injection-locked oscillators that can be synchronized by a small injection signal of either wireless or optical origin, and thus, can transfer phase encoded information from wireless to the optical domain or the optical to the wireless domain.
- Self-oscillation and period adding from resonant tunnelling diode–laser diode circuitPublication . Figueiredo, J. M. L.; Romeira, Bruno; Slight, Thomas James; Wang, Liquan; Wasige, Edward; Ironside, C. N.A hybrid optoelectronic integrated circuit comprising a laser diode driven by a resonant tunnelling diode can output various optical and electrical signal patterns that include self-sustained oscillations, subharmonic and harmonic locking and unlocked signals, with potential applications in optical communication systems.
- Synchronisation and chaos in a laser diode driven by a resonant tunnelling diodePublication . Romeira, Bruno; Figueiredo, J. M. L.; Slight, Thomas James; Wang, Liquan; Wasige, Edward; Ironside, C. N.; Quintana, J. M.; Avedillo, M. J.The authors report on a hybrid integration of a resonant tunnelling diode laser diode driver configuration that can operate as a self-oscillating circuit, and when externally perturbed shows regions of frequency division and frequency multiplication, quasi-periodic and chaotic oscillations, both in the optical and electrical outputs. The authors also demonstrate that this optoelectronic circuit is well described as a Lie´nard’s oscillator. The synchronisation capabilities of the circuit have potentially novel functions for optical communications systems including clock recovery, clock division and data encryption.