Browsing by Subject "Time-based"
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Item Design of a time-based sigma-delta modulator(2010-08) Dutta, Arnab Kumar, 1984-; Hassibi, Arjang; Swanson, EricIn this thesis, a time-based oversampling sigma-delta analog-to-digital converter (ADC) architecture is introduced. This system uses time, instead of voltage, as the analog variable for it quantizer, where the noise shaping process is realized by modulating the width of a variable-width digital pulse. The sigma-delta loop integrator, comparator, and subtractor are all time-based circuits and implemented by using only digital gates. The only voltage-based circuit is voltage-to-time Converter (VTC) which requires only a current source. No amplifier is required in the entire circuit. As a proof of concept, the simulation results for a prototype ADC incorporating this time-based sigma-delta ADC architecture is presented.Item VCO-based analog-to-digital conversion(2012-12) Hamilton, Joseph Garrett; Hassibi, Arjang; Viswanathan, T. R., doctor of electrical engineeringThis dissertation presents a novel [delta sigma] analog-to-digital converter architecture which replaces the operational amplifier-based integrator with a pair of tunable oscillators. A switched-capacitor V-I converter is used to combine the input voltage with a feedback DAC output and convert it into a current for two pseudo-differential current-controlled oscillators. The oscillator outputs are counted with a digital counter, and a digital back-end [delta sigma] modulator is used to truncate the high-resolution counter outputs for the feedback DAC path. This architecture has compelling advantages in deep sub-micron and emerging technologies where supply voltages are decreasing to a point that traditional analog architectures are no longer feasible. Additionally, this architecture takes advantage of the increased speed in these short-channel technologies. Measured results on a 6.08mW prototype in TSMC 0.18um achieving 63.5dB in a 2MHz bandwidth are presented.