Abstract: A switching apparatus for switching between channels within a read/write pre-amplifier circuit in a multi-channel magnetic media storage system switches between the channels and couples an active magnetoresistive sensor to receive biasing current and to a pre-amplifier circuit. When a read operation is requested from a specific channel within the magnetic media storage system, a control signal line corresponding to an appropriate magnetoresistive sensor is activated. Each channel includes a first corresponding transistor which is enabled by an appropriate control signal line, allowing current to flow through the first transistor to enable a second corresponding transistor that is coupled to the magnetoresistive sensor. Once enabled the second transistor couples the magnetoresistive sensor to a pre-amplifier stage and to receive biasing current.

Abstract: A single-ended input amplifier circuit for use within a magnetic media storage system includes circuits for concurrently biasing and amplifying signals generated by a magnetoresistive element. The amplifier receives power from a single-ended power supply. A first resistor is included for setting the gain of the amplifier and providing an output signal corresponding to the signals generated by the magnetoresistive element. A first feedback circuit generates a first biasing current provided to the magnetoresistive element. The first feedback circuit includes a first transconductance amplifier which amplifies the difference between the output signal and a reference voltage. A second feedback circuit generates a second biasing current provided to the magnetoresistive element. The second feedback circuit includes a second transconductance amplifier which amplifies the difference between the reference voltage and a voltage signal taken from a node between two resistors.