Magnetic head having a hall effect sensor and circuit for detecting recorded bits from magnetic recording media

A disk drive, comprising:

• a slider;
• a magnetic head carried on the slider;
• a read head portion of the magnetic head;
• the read head portion including a Hall effect sensor;
• the Hall effect sensor having:
• a generally planar body made of a semiconductor heterostructure;
• a first contact comprising a first drain formed over a first end of the body;
• a second contact comprising a second drain formed over the first end of the body;
• the first and the second contacts being spaced equally apart from a centerline of the body;
• a third contact comprising a source formed over a second end of the body which is opposite the first end of the body;
• the Hall effect sensor being carried by the slider at an air bearing surface (ABS), such that the body is exposed to magnetic field signals substantially normal thereto from a magnetic disk which has a plurality of recorded bits with at least one of a first bit polarity and a second bit polarity;
• a first resistor coupled between a reference voltage and the first contact;
• a second resistor coupled between the reference voltage and the second contact;
• a current source coupled to the third contact and adapted to produce a current 2I through the body, such that the first drain has a first current I1=I−i and the second drain has a second current I2=I+i, where i is a differential current which varies based on whether the magnetic field signals correspond to a recorded bit having the first bit polarity or the second bit polarity;
• and
• a voltage output taken between the first and the second contacts and providing a differential voltage which varies based on whether the magnetic field signals correspond to a recorded bit having the first bit polarity or the second bit polarity.