Parallel conversion of signal through a low res & fast ADC and high res & slow ADC
GREAT, I have found a very recent book on this, if you are interested. It is called dual path parallel sampling / parallel sampling : 

Power-Efficient High-Speed Parallel-Sampling ADCs for Broadband Multi-carrier Systems (Analog Circuits and Signal Processing)

'The authors focus on exploiting the a-priori knowledge of the system/application to develop enhancement techniques for ADCs, with particular emphasis on improving the power efficiency of high-speed and high-resolution ADCs for broadband multi-carrier systems.'

Implementations of the merits of parallel pipelined low res and SAR high res are discussed. Particularly good for increasing the dynamic range.