Patent ID: 6125094
Filing Date: 2000-09-26
Classification: G11B,H03F

Abstract:
A compact disk system for reading data from a compact disk, the system comprising:a motor to rotate the compact disk;a servo motor positionable in proximity with the compact disk;a read head coupled to said servo motor to detect data patterns from the compact disk, said read head generating a data current signal in response to said data patterns; anda preamplifier coupled to said read head to amplify said data current signal, said preamplifier comprising:a cascode transistor for fixing the voltage of an input of the amplifier;a first constant current source connected between the input and a first supply voltage;a second constant current source, for providing a current lower than the first current source, connected between a second supply voltage and the cascode transistor;a second transistor, of different type than the cascode transistor, connected between the input and the second supply voltage, and controlled by the node between the cascode transistor and the second current source; andan output transistor of same type as the second transistor, connected to the second supply voltage and controlled by said node.