An integrated single-sideband modulator is used as the sole wide-bandwidth frequency actuator in a Pound-Drever-Hall locking loop. Thanks to the large modulation bandwidth, the device enables a locking range of ±75 MHz and a control bandwidth of 5 MHz without the need for a second feedback loop. As applied to the coupling of an extended-cavity diode laser at 1.55 μm to a high-finesse optical cavity, the in-loop frequency noise spectral density reaches a minimum of 1 mHz/Hz(1/2) at 1 kHz.