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With superconducting transmon qubits --- a promising platform for quantuminformation processing --- two-qubit gates can be performed using AC signals tomodulate a tunable transmon's frequency via magnetic flux through its SQUIDloop. However, frequency tunablity introduces an additional dephasing mechanismfrom magnetic fluctuations. In this work, we experimentally study thecontribution of instrumentation noise to flux instability and the resultingerror rate of parametrically activated two-qubit gates. Specifically, wemeasure the qubit coherence time under flux modulation while injectingbroadband noise through the flux control channel. We model the noise's effectusing a dephasing rate model that matches well to the measured rates, and useit to prescribe a noise floor required to achieve a desired two-qubit gateinfidelity. Finally, we demonstrate that low-pass filtering the AC signal usedto drive two-qubit gates between the first and second harmonic frequencies canreduce qubit sensitivity to flux noise at the AC sweet spot (ACSS), confirmingan earlier theoretical prediction. The framework we present to determineinstrumentation noise floors required for high entangling two-qubit gatefidelity should be extensible to other quantum information processing systems.

Assessing the Influence of Broadband Instrumentation Noise on Parametrically Modulated Superconducting Qubits