We present a feedback-control method for suppression of excess phase noise in the optical-to-electronic conversion process involved in the extraction of microwave signals from femtosecond mode-locked lasers. A delay-locked loop based on drift-free phase detection with a differentially biased Sagnac loop is employed to eliminate low-frequency (e.g., $<1\mathrm{kHz}$ ) excess phase noise and drift in the regenerated microwave signals. A $10\mathrm{GHz}$ microwave signal is extracted from a $200\mathrm{MHz}$ repetition rate mode-locked laser with a relative rms timing jitter of $2.4\mathrm{fs}$ (integrated from $1\mathrm{mHz}$ to $1\mathrm{MHz}$ ) and a relative rms timing drift of $0.84\mathrm{fs}$ (integrated over $8\mathrm{h}$ with $1\mathrm{Hz}$ bandwidth) between the optical pulse train and the extracted microwave signal.