Why Analog-to-digital converters come in a handful of standard architectures: successive approximation (SAR), flash/parallel, sigma-delta, and dual-slope integrating. A SAR converter uses a comparator and an internal DAC to perform a binary search, testing the most significant bit first and working down, so an N-bit conversion takes N comparison steps. That trade of speed for simplicity makes it the most common general-purpose ADC design.
Watch out Level shifting is the tempting one, but it only moves an analog signal's DC offset so it fits a device's input range; it is a preparation step, not the conversion itself. Harmonic regeneration and phase reversal are not conversion methods at all.
ADC families to know: successive approximation, flash, sigma-delta. SAR = binary search, one bit per step.