Photonic Front-End and Comparator Processor for a Sigma-Delta Modulator
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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This thesis examines the role of photonics and integrated optics IO for use in analog-to-digital conversion in electronic warfare EW intercept receivers. The IO approach uses a continuous wave CW distributed feedback DFB laser diode at a peak wavelength of 1550 nm to oversample two Mach-Zehnder interferometers MZIs. The MZIs are part of sigma-delta modulator-based analog-to-digital converter ADC oversampling architecture. A ring resonator accumulator is embedded within a feedback loop in the modulator to spectrally shape the quantization noise of the system. The experimental and simulation results are evaluated as a narrow-band proof of concept for the use of photonics technology in the sampling of wide-band radio frequency RF signals. Taking the characteristics of the real components and the experimental results, a pulse to pulse computer simulation of an oversampled first-order single-bit modulator was accomplished using RSoft OptSim. The performance characteristics of this subsystem were compared with the narrow-band results produced in the laboratory. In addition, a comparator processor circuit for the signal oversampling subsystem was designed and simulated in SIMUCAD SmartSpice. The analysis of the comparator processor circuit was evaluated. The lack of high-speed components limited the experimental and simulation results. With the system integrated with high-speed components, a wide-band direct digital antenna architecture can be demonstrated.
- Electrical and Electronic Equipment
- Fiber Optics and Integrated Optics