Animal propulsors such as wings and fins bend during motion and these bending patterns are believed to contribute to the high efficiency of animal movements compared with those of man-made designs. However, efforts to implement flexible designs have been met with contradictory performance results. Consequently, there is no clear understanding of the role played by propulsor flexibility or, more fundamentally, how flexible propulsors should be designed for optimal performance. Here we demonstrate that during steady-state motion by a wide range of animals, from fruit flies to humpback whales, operating in either air or water, natural propulsors bend in similar ways within a highly predictable range of characteristic motions. By providing empirical design criteria derived from natural propulsors that have convergently arrived at a limited design space, these results provide a new framework from which to understand and design flexible propulsors.

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This thesis presents the design and implementation of an All-Digital Phase Locked Loop (ADPLL) that uses Delta-Sigma (ΔΣ) modulation, multi-phase outputs, and Dynamic Element Matching (DEM). The system is designed using a combination of 65nm CMOS technology and an FPGA. The frequency range of the ADPLL output is 5.48GHz to 6.22GHz. Several design techniques are used to reduce the phase noise of the ADPLL output. The ADPLL uses a rotary travelling wave-based Digitally Controlled Oscillator (DCO) with multi-phase outputs to improve quantization noise. Manufacturing variations on the fine-tuning DCO input capacitors are averaged using DEM to produce more uniform frequency steps. ΔΣ modulation is used on the least significant of the DCO input bits. This modulation introduces a dithering effect on the output frequency that has the effect of moving some of the phase noise away from the ADPLL carrier frequency.