Digital mismatch compensation in Time-Interleaved ADCs
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Time-Interleaved Analog-to-Digital Converters (TIADC) appear to be a very promising way to achieve high rate and high resolution analog-to-digital conversion. The principle is to have several lower sampling rate ADCs operating in parallel. However, this architecture suffers from mismatch noise because the characteristics of the ADCs differ slightly. We develop a frequency model to show the effects of these mismatches on the output spectrum of the TIADC. For that, we derive, for each type of mismatch (offset, gain, skew and bandwidth), expressions of the output spectrum in function of the input spectrum and the mismatch coefficients. We then demonstrate that this model can be used to help determine the allowed level of mismatches in function of the expected performances.
Compensating the mismatch noise in the digital domain has been a challenge for a few years and this would allow for a very flexible TIADC design if low computational cost solutions would exist. In this work, we propose blind digital methods to compensate offset, gain and skew mismatches. The gain and offset compensation techniques are based on averaging respectively the output samples and the squared output samples of the sub-ADCs. They achieve good performances on almost any type of input signal at relatively low computational costs. The proposed skew compensation method is more complex and has still to be investigated further but the preliminary results are very promising.
Place, publisher, year, edition, pages
EES Examensarbete / Master Thesis, XR-EE-SB- 2012:008
Time-Interleaved ADC, offset, gain, skew, bandwidth, mismatch, blind, digital
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-98799OAI: oai:DiVA.org:kth-98799DiVA: diva2:539115
Master of Science in Engineering - Microelectronics
Händel, Peter, Professor