  CEPC (Circular Electron and Positron Collider) is a large experiment facility
proposed by Chinese particle physics community. One of its running option is
being the Higgs factory. Calorimeter is the main part of this experiment to
measure the jet energy. Semi-digital hadron calorimeter (SDHCAL) is one of the
options for the hadron measurement. GEM detector with its high position
resolution and flexible configuration is one of the candidates for the active
layer of the SDHCAL. The main purpose of this paper is to provide a feasible
readout method for the GEM-based semi-digital hadron calorimeter. A small-scale
prototype is designed and implemented, including front-end board (FEB) and data
interface board (DIF). The prototype electronics has been tested. The
equivalent RMS noise of all channels is below 0.35fC. The dynamic range is up
to 500fC and the gain variation is less than 1%. The readout electronics is
applied on a double-layer GEM detector with 1cm*1cm readout pad. Result
indicates that the electronics works well with the detector. The detection
efficiency of MIP is over 95% with 5fC threshold.
