Uk. Moon et Bs. Song, BACKGROUND DIGITAL CALIBRATION TECHNIQUES FOR PIPELINED ADCS, IEEE transactions on circuits and systems. 2, Analog and digital signal processing, 44(2), 1997, pp. 102-109
A skip and fill algorithm is developed to digitally self-calibrate pip
elined analog-to-digital converters (ADC's) in real time, The proposed
digital calibration technique is applicable to capacitor-ratioed mult
iplying digital-to-analog converters (MDAC's) commonly used in multist
ep or pipelined ADC's, This background calibration process can replace
, in effect, a trimming procedure usually done in the factory with a h
idden electronic calibration, Unlike other self-calibration techniques
working in the foreground, the proposed technique is based on the con
cept of skipping conversion cycles randomly but filling in data later
by nonlinear interpolation, This opens up the feasibility of digitally
implementing calibration hardware and simplifying the task of self-ca
librating multistep or pipelined ADC's, The proposed method improves t
he performance of the inherently fast ADC's by maintaining simple syst
em architectures, To measure errors resulting from capacitor mismatch,
op amp de gain, offset, and switch feedthrough in real time, the cali
bration test signal is injected in place of the input signal using a s
plit-reference injection technique. Ultimately, the missing signal wit
hin two-thirds of the Nyquist bandwidth is recovered with 16-b accurac
y using a forty-fourth order polynomial interpolation, behaving essent
ially as an FIR filter.