Kawasaki Heavy Industries, Ltd. has developed a digitally-controlled servo amplifier for robot servo motors. The motor’s armature current, position and velocity are controlled by the software in a digital signal processor. The servo is designed for high reliability, performance, flexibility and compactness. To achieve these objectives, we developed an ASIC which controls PWM signals for power transistors and encoder signals. The servo amplifier is currently used in the new Kawasaki AD series of robot controllers.