ATLAS is a particle physics experiment at the Large Hadron Collider (LHC) that detects proton-proton collisions at a centre of mass energy of 14 TeV. The Semiconductor Tracker is part of the Inner Detector, implemented using silicon microstrip detectors with binary read-out, providing momentum measurement of charged particles with excellent resolution. The operation of the LHC and the ATLAS experiment started in 2010, with ten years of operation expected until major upgrades are needed in the accelerator and the experiments. The ATLAS tracker will need to be completely replaced due to the radiation damage and occupancy of some detector elements and the data links at high luminosities. These upgrades after the first ten years of operation are named the Phase-II Upgrade and involve a re-design of the LHC, resulting in the High Luminosity Large Hadron Collider (HL-LHC). This thesis presents the work carried out in the testing of the ATLAS Phase-II Upgrade electronic systems in the future strips tracker after 2023, to be installed for operations in the HL-LHC period. The high luminosity and number of interactions per crossing that will happen after the HL-LHC starts require a complete replacement of the ATLAS tracker. The systems that have been defined for the Phase-II Upgrade will be designed to cope with that increased radiation and have the right granularity to maintain the performance with higher pile-up. In this thesis I present results on single modules and larger structures comprising multiple modules. The single modules are built using silicon microstrip sensors with four rows of 1280 strips. The read-out of the strips is done using 128 channel chips, glued and bonded on a hybrid circuit that holds 20 chips. Two hybrids are glued to the sensor to read-out all its strips. In addition to the new sensors and read-out chips, the specifications for the ATLAS Phase-II Upgrade programme require a different powering scheme in the strips tracker than the current ATLAS Semiconductor Tracker. Two approaches have been proposed, which are serial powering and Direct Current to Direct Current (DC-DC) conversion. The decision on which will be used is not final yet, pending the results on efficiency and performance of the tracker using both of them. Larger structures are constructed by mounting the single modules on a bus tape that carries the signals to one end of the structure, which interfaces with the tracker read-out systems. The bus tape is glued on a structure that provides mechanical support and cooling. All the modules on a structure are read-out through the same interface, aggregating multiple signals in one physical channel. The structures are called staves or stavelets. The latter typically mount four modules on a side of the structure. Two different stavelets have been tested in the context of this thesis, one with serial powering and one with DC-DC conversion. Both are single-sided objects and double-sided objects have been constructed and tested in other institutes. One full size stave with twelve modules on one side has been constructed. It is powered using DC-DC conversion, and tested at the Rutherford Appleton Laboratory (RAL) as part of the work for this thesis. In the context of the current ATLAS Semiconductor Tracker studies, I present an analysis of the data taken by the detector from the beginning of operation in 2010 until the first Long Shut-down in 2013. The analysis consists of an energy loss study in the Semiconductor Tracker, a task the detector was not designed to perform. However, the availability of the Time-over-Threshold of the signals generated by particles traversing the detector elements allows an estimation of the charge deposited by the particles. This calculation of the energy loss is typically used to perform particle identification, a feature that is usually not required from the tracker. In addition, I present a study that proposes the use of this energy loss calculation as a means of tracking radiation damage in the silicon.