Baecker, MoritzMoritzBaeckerJaeger, MarvinMarvinJaegerTegowski, BartoszBartoszTegowskiRiemschneider, Georg F.Georg F.RiemschneiderKoelpin, AlexanderAlexanderKoelpin2026-06-222026-06-222026-0317th German Microwave Conference, GeMiC 2026https://hdl.handle.net/11420/63604This paper presents an analog microwave frontend designed to downconvert and feed back the control signal for trapped ion qubits, which are frequency-multiplexed by the magnetic gradient induced coupling (MAGIC) principle. Shorter gate durations require a higher excitation signal power, increasing distortion caused by nonlinear components. The proposed feedback receiver serves the purpose of coupling out a portion of the generated qubit control signal to feed it back into the signal generation hardware. This enables closed-loop signal processing techniques to compensate for nonlinearities in signal generation, thus improving the idle fidelity of untargeted qubits. The characterization of a manufactured prototype is performed, followed by an active cancellation of spurious tones based on the downconverted qubit control signal to demonstrate the capability for qubit fidelity improvement.enFidelitymagnetic gradient induced coupling (MAGIC)microwave frontendquantum computingqubitreceiversTechnology::621: Applied Physics::621.3: Electrical Engineering, Electronic Engineering::621.38: Electronics, Communications EngineeringConference Paper10.1109/GeMiC71240.2026.11516472