  We have developed a dedicated front-end-electronics board for a high-pressure
xenon gas time projection chamber for a neutrinoless double-beta decay search.
The ionization signal is readout by detecting electroluminescence photons with
SiPM's. The board readout the signal from 56~SiPM's through the DC-coupling and
record the waveforms at 5 MS/s with a wide dynamic range up to 7,000
photons/200 ns. The SiPM bias voltages are provided by the board and can be
adjusted for each SiPM. In order to calibrate and monitor the SiPM gain,
additional auxiliary ADC measures 1 photon-equivalent dark current. The
obtained performance satisfies the requirement for a neutrinoless double-beta
decay search.
