  Measurement of charge configurations in few-electron quantum dots is a vital
technique for spin-based quantum information processing. While fast and
high-fidelity measurement is possible by using proximal quantum dot charge
sensors, their operating range is limited and prone to electrical disturbances.
Here we demonstrate realtime operation of a charge sensor in a feedback loop to
maintain its sensitivity suitable for fast charge sensing in a Si/SiGe double
quantum dot. Disturbances to the charge sensitivity, due to variation of gate
voltages for operating the quantum dot and $1/f$ charge fluctuation, are
compensated by a digital PID controller with the bandwidth of $\approx
100\,{\rm kHz}$. The rapid automated tuning of a charge sensor enables
unobstructed charge stability diagram measurement facilitating realtime quantum
dot tuning and submicrosecond single-shot spin readout without compromising the
performance of a charge sensor in time-consuming experiments for quantum
information processing.
