Speed control of a permanent magnet synchronous machine (PMSM) drive system has been presented in this paper based on single control loop using the second order active disturbance rejection control (ADRC) scheme. The proposed control scheme simplifies the motor control system by avoiding the cascaded loops to provide fast and robust rejection of the load disturbances. Furthermore, a simple design criterion of the proposed control scheme has been formulated that guarantees the drive system stability with high dynamic performance. The practical implementation of the proposed control scheme makes it suitable for current PMSM drive system. The dynamic performance of the proposed controller and its tuning criterion have been discussed analytically and validated through comprehensive simulation results.