Compensation of mismatch errors in a time-interleaved analog-to-digital converter
AssigneeSignal Processing Devices Sweden AB
InventorsHåkan Johansson, Per Löwenborg
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Abstract
A method for the compensation of frequency-response mismatch errors in M-channel time-interleaved ADCs. The compensation is done through an M-periodic time-varying filter hn(k)=hn mod M(k) (2), or, equivalently, a set of M time-invariant filters hn(k), n=0, 1, . . . , M−1. The overall compensation system is constructed by determining the M filter impulse responses hn(k) through M separate matrix inversions, where the size of the matrices equals the filter impulse response length. Also, a compensated M-channel time-interleaved ADC based on and performing the method.
Claims23
A method for compensating frequency response mismatch errors in an M-channel time-interleaved analog-to-digital converter comprising M analog-to-digital converters (11-1M) in an array and a filter connected to the output of the time-interleaved analog-to-digital converter, the method comprising:
- determining M frequency responses Qr from said M-channels, calculating separately M channel impulse responses hr for said M-channels, calculating matrix elements of M matrices Sr and vectors cr being factors of error power functions Pr,
- minimizing said power functions Pr by inverting separately said M matrices Sr,
- forming M output subsequences utilizing convolutions of the impulse responses being calculated separately and the output of the time-interleaved analog-to-digital converter, and
- forming an overall output from the compensated time-interleaved analog-to-digital converter by interleaving output subsequences yr of the channels.
A compensated analog-to-digital time-interleaved converter comprising:
- a number of M channels,
- each channel including an analog-to-digital converter (11-1M), and
- a filter (21-2M),
- wherein the converter is configured to perform a method for compensating frequency response mismatch errors in the converter comprising
- determining M frequency responses Qr from said M-channels,
- calculating separately M channel impulse responses hr for said M-channels,
- calculating matrix elements of M matrices Sr and vectors cr being factors of error power functions Pr,
- minimizing said power functions Pr by inverting separately said M matrices Sr,
- forming M output subsequences utilizing convolutions of the impulse responses being calculated separately and the output of the interleaved analog-to-digital converter, and
- forming an overall output from the compensated interleaved analog-to-digital converter by interleaving output subsequences yr of the M channels.
Dependencies are inferred from the claim text.