Date of Award
Doctor of Philosophy
Electrical and Computer Engineering
A novel harmonic management technique in Phase Shift Oscillators (PSO) is proposed. The technique can be used to generate multi-phase, square waves, low distortion sine waves or perform frequency multiplication or division for frequency synthesis. The technique involves weighted-summation of the PSO's outputs to obtain an overall output that consists of the desired harmonics. A detailed derivation is provided that allows the user to choose the weights for the desired harmonic content. Robustness of the proposed technique is demonstrated using systematic analysis and simulations. In this work, the focus is on using the proposed technique to generate low distortion sine waves. A bread board prototype of a low distortion sine generator has been implemented using the proposed technique. The sine wave generator can generate -100dB Total Harmonic Distortion (THD) sine waves using extremely low cost discrete components. Simulations of on-chip sine wave generators implemented in a 0.13um CMOS technology process demonstrate using the proposed technique to generate -80dB THD sinusoids with large voltage swing.
The second part of the dissertation focuses on testing of Integral non-linearity (INL) of Analog-to-Digital Converters (ADC). The proposed algorithms reduce test cost associated with expensive hardware, and test cost associated with test time. Low cost voltage-shift generators that can enable testing of High resolution ADCs are investigated. It is shown that with the proposed shift generator and low linearity stimuli, INL of ADCs with resolution as high as 16-bit can be characterized.
The last part of the dissertation focuses on sensor interface circuits for soft elastomeric capacitors (SEC) for Structural Health Monitoring (SHM) applications. Each SEC is a flexible strain gauge, transducing a change in strain into a change in capacitance. The proposed measurement method relies on the differential measurement technique. A prototype of the proposed technique has been built to demonstrate the working under controlled strains. The circuit has a voltage sensitivity to strain of 23mV/με.
Bharath Karthik Vasan
Vasan, Bharath Karthik, "Waveform generation in phase shift oscillators using harmonic programming techniques" (2013). Graduate Theses and Dissertations. 13460.