The ATLAS Liquid Argon Calorimeter electronics will be upgraded to readout the 182,500 calorimeter cells at 40 MHz with 16 bit dynamic range in the high pileup conditions of the high-luminosity LHC. Low-noise, low-power, radiation-tolerant and high-bandwidth electronics components are being developed in 65 and 130 nm CMOS technologies. The off-detector electronics will make use of FPGAs connected through high-speed links to perform energy reconstruction, data reduction and buffering. Results of tests of the first prototypes of front-end components will be presented, along with design studies on the performance of the off-detector readout system.