In this work, we propose and simulate a novel amplifier based on Weyl semi-metals, e.g. WP2 and MoP2. These topological materials have been shown to exhibit extremely large magnetoresistance at cryogenic conditions. In the proposed device, a gate current induces a local magnetic field which controls the resistivity of the Weyl semi-metal channel and the resulting output current. Simulations of the magnetic fields are performed to optimize the device design, as well as thermal modeling to determine self-heating effects. Device operation is simulated using an analytical 3D model of magnetic fields and resistivity, and a small-signal model. Results show that the proposed device can provide high gain (20-30 dB) with extremely low DC power dissipation (40 μW) and high transition frequencies. This type of device is promising to replace HEMTs in quantum computers, where the low power dissipation enables it to be integrated at lower cryostat temperature stages.