pipeline converter
Pipeline converters are multi-stage A/D converters consisting of several flash converters. Their advantages are the high resolution, which reaches up to 14 bits, and the high sampling rate, which can be 100 MHz and more.
In terms of structure, the pipeline converter is a cascading of several flash converters. Each individual parallel converter quantizes the differential signal of the upstream A/D converter. The first A/D converter receives the input signal to be digitized, quantizes it and represents the higher order bits of the digital output.
The digital output signal is converted into an analog signal in a D/A converter, temporarily stored in a sample-and-hold circuit, subtracted from the original input signal and, after amplification, fed to the next parallel converter, which quantizes the differential signal with higher resolution. The further downstream A/D converters quantize the next difference signal in each case and with ever higher resolution. After passing through all pipeline stages, the result is calculated.
The high dynamic range of the pipeline converter requires high linearity of the individual A/D converters and precise amplifiers that amplify the differential signal between the pipeline stages. Pipeline converters achieve higher resolutions than flash converters with a comparable number of comparators, but this comes at the cost of conversion time. However, since each pipeline stage holds the conversion value in the sample-and-hold circuit, multiple cycles can occur simultaneously, which puts the conversion speed into perspective.