  In semiconductor spin quantum bits (qubits), the radio-frequency (RF)
gate-based readout is a promising solution for future large-scale integration,
as it allows for a fast, frequency-multiplexed readout architecture, enabling
multiple qubits to be read out simultaneously. This paper introduces a
theoretical framework to evaluate the effect of various parameters, such as the
readout probe power, readout chain's noise performance, and integration time on
the intrinsic readout signal-to-noise ratio (SNR), and thus readout fidelity of
RF gate-based readout systems. By analyzing the underlying physics of spin
qubits during readout, this work proposes a qubit readout model that takes into
account the qubit's quantum mechanical properties, providing a way to evaluate
the trade-offs among the aforementioned parameters. The validity of the
proposed model is evaluated by comparing the simulation and experimental
results. The proposed analytical approach, the developed model, and the
experimental results enable designers to optimize the entire readout chain
effectively, thus leading to a faster, lower-power readout system with
integrated cryogenic electronics.
