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    Investigation, design and fabrication of miniaturized CMOS novel active RFID tags : Doctor of Philosophy in Engineering-Electronics, Information and Communication Systems at Massey University, Albany campus
    (Massey University, 2021) Kumari, Meera
    The drastic decline in the bee population in the past few years is alarming given the quantity and quality of global food reliance on these insect pollinators. To ensure sustainable crop production and maintain biodiversity, it has become an important area of research for entomologists to study the factors involved in the dramatic population decline of these tiny insects. Understanding the insect’s biology and their foraging behavior tracking in the agricultural landscape is crucial. However, due to the large size of the available PCB-based tracking tags knowing their true behaviours in the presence of various chemical fertilizers and pesticides is still a challenge. In this research, a very new VHF radio telemeter architecture has been developed which could facilitate tracking of a large number of small insects and bees wirelessly in real-time at a distance of around 1km. The architecture is based on a novel circuit topology to generate an extremely low duty cycle signal digitally which for the first time does not require any passive elements. This digital generation technique of the low duty cycle has made it possible to realize the complete telemeter design on 1mmX 1mm ASIC chip, except for the antenna and the battery, and eliminated the need for discreet components which are mounted on PCB. Due to inconsistent fabrication facilities, the telemeter circuit parts were implemented in CMOS8RF-130nm and 8HPP-28nm, but the final ASIC telemeter prototype is realized in TSMC 65nm process technology and the fabricated chip is experimentally tested in the lab to verify its performance in the manufacturing environment. The design consists of a digital core circuit to generate 8-bit binary-coded 0.0078 duty-cycled burst mode signaling and a full on-chip analog power management circuit to locally generate the required voltage supplies with predefined dependence on temperature for the digital circuitry with the compensation for the temperature variation on the telemeter performance. A white paper calculation has been presented to package the insect telemeter ASIC, along with 10cm antenna directly over 80mg, 5mmX5mmX1mm silver oxide battery to yield a 95mg complete telemeter package, making it to be the world’s smallest and the lightest VHF radio telemeter.
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    Design of a novel X-section architecture for FX-correlator in large interferometers : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Auckland, New Zealand
    (Massey University, 2021) Balu, Vignesh Raja
    In large radio-interferometers it is considerably challenging to perform signal correlations at input data-rates of over 11 Tbps, which involves vast amount of storage, memory bandwidth and computational hardware. The primary objective of this research work is to focus on reducing the memory-access and design complexity in matrix architectural Big Data processing of the complex X-section of an FX-correlator employed in large array radio-telescopes. This thesis presents a dedicated correlator-system-multiplier-and -accumulator (CoSMAC) cell architecture based on the real input samples from antenna arrays which produces two 16-bit complex multiplications in the same clock cycle. The novel correlator cell optimization is achieved by utilizing the flipped mirror relationship between Discrete Fourier transform (DFT) samples owing to the symmetry and periodicity of the DFT coefficient vectors. The proposed CoSMAC structure is extended to build a new processing element (PE) which calculates both cross- correlation visibilities and auto-correlation functions simultaneously. Further, a novel mathematical model and a hardware design is derived to calculate two visibilities per baseline for the Quadrature signals (IQ sampled signals, where I is In-phase signal and Q is the 90 degrees phase shifted signal) named as Processing Element for IQ sampled signals (PE_IQ). These three proposed dedicated correlator cells minimise the number of visibility calculations in a baseline. The design methodology also targets the optimisation of the multiplier size in order to reduce the power and area further in the CoSMAC, PE and PE_IQ. Various fast and efficient multiplier algorithms are compared and combined to achieve a novel multiplier named Modified-Booth-Wallace-Multiplier and implemented in the CoSMAC and PE cells. The dedicated multiplier is designed to mostly target the area and power optimisations without degrading the performance. The conventional complex-multiplier-and-accumulators (CMACs) employed to perform the complex multiplications are replaced with these dedicated ASIC correlator cells along with the optimized multipliers to reduce the overall power and area requirements in a matrix correlator architecture. The proposed architecture lowers the number of ASIC processor cells required to calculate the overall baselines in an interferometer by eliminating the redundant cells. Hence the new matrix architectural minimization is very effective in reducing the hardware complexity by nearly 50% without affecting the overall speed and performance of very large interferometers like the Square Kilometre Array (SKA).