Demonstrator model of the warm front-end electronics for the ATHENA mission's X-IFU instrument

The X-ray integral field unit (X-IFU) is one of the two instruments of ESA's ATHENA space mission. It is a cryogenic X-Ray spectro-imager with an unprecedented 2.5 eV resolution up to 7 keV. We present the development of the demonstrator model (DM) of X-IFU's warm front-end electronics (WFEE). X-IFU will have around 2400 cryogenic micro-calorimeters divided into 72 time-division multiplexed (TDM) channels. The main functions of the WFEE are providing the biasing currents for the detectors and two SQUID stages and to amplify the SQUIDs output signals. Each channel requires 5 current sources (quasi-DC DACs) and a fully differential low-noise voltage amplifier (LNA). The DACs can be written and read via an I2C bus. The active component of the WFEE is the AwaXe ASIC, which was specifically designed for this project and integrates current DACs and LNAs for two TDM channels. The WFEE has also to provide housekeeping signals for power supply voltage, and on-chip ASIC temperature. Both, the final expected performances of the instrument and the general specifications of a space mission, impose strong requirements on the WFEE in terms of thermal stability, mechanical design, radiation hardness, raw performance and reliability. To validate some of these requirements, a demonstrator model of the WFEE is currently being developed to be integrated in a full readout chain for lab testing. In this paper we will discuss the PCB and mechanical assembly designs of the WFEE demonstrator model in preparation of the ATHENA space mission.