Method and apparatus to remove the DC component of a feedback signal

A method of reducing DC component of a feedback signal flowing through a feedback circuit disposed across an input terminal and an output terminal of an amplifier, the method comprising:

• supplying a current to a terminal of a transistor;
• said terminal being in communication with the input terminal of the amplifier;
• flowing the current from a second terminal of the transistor to a voltage source;
• and
• maintaining substantially equal voltages across first and second terminals of a resistive load disposed between the second terminal of the transistor and the output terminal of the amplifier.

A feedback circuit disposed across an input terminal and an output terminal of an amplifier, the feedback circuit comprising:

• means for supplying a current to a first terminal of a transistor, said means being in communication with the input terminal of the amplifier;
• means for flowing the current from a second terminal of the transistor to a voltage supply;
• and
• means for maintaining substantially equal voltages across first and second terminals of a resistive load disposed between the second terminal of the transistor and the output terminal of the amplifier.

A differential amplifier comprising:

• a first feedback circuit disposed across a first input terminal of the amplifier and a first output terminal of the amplifier, the first feedback circuit comprising:
• a first transistor;
• a first current source supplying a first current to a first terminal of the first transistor, said first current source being in communication with the first input terminal of the amplifier;
• a second current source receiving the first current from a second terminal of the first transistor and supplying the received current to a voltage source;
• and
• a first resistive load having a first terminal in communication with the second terminal of the transistor and a second terminal in communication with the first output terminal of the amplifier;
• said first and second terminals of the first resistive load having DC voltages characterized substantially by a first value;
• and
• a second feedback circuit disposed across a second input terminal of the amplifier and a second output terminal of the amplifier, the second feedback circuit comprising:
• a second transistor;
• a third current source supplying a second current to a first terminal of the second transistor, said third current source being in communication with the second input terminal of the amplifier;
• a fourth current source receiving the second current from a second terminal of the second transistor and supplying the received second current to a voltage source;
• and
• a second resistive load having a first terminal in communication with the second terminal of the second transistor and a second terminal in communication with the second output terminal of the amplifier;
• said first and second terminals of the second resistive load having DC voltages characterized substantially by a second value.

A method of reducing DC component of feedback signals flowing through a pair of feedback circuits disposed across a pair of input terminals and a pair of output terminals of an amplifier, the method comprising:

• supplying a first current to a first terminal of a first transistor;
• said first terminal being in communication with a first input terminal of the amplifier;
• flowing the first current from a second terminal of the first transistor to a first voltage source;
• supplying a second current to a first terminal of a second transistor;
• said first terminal of the second transistor being in communication with a second input terminal of the amplifier;
• flowing the second current from a second terminal of the second transistor to a second voltage source;
• maintaining substantially equal voltages across first and second terminals of a first resistive load disposed between the second terminal of the first transistor and a first output terminal of the amplifier;
• and
• maintaining substantially equal voltages across first and second terminals of a second resistive load disposed between the second terminal of the second transistor and a second output terminal of the amplifier.

A system comprising:

• a storage media driver having disposed therein a reader head;
• a transimpedance amplifier responsive to the reader head;
• and
• a feedback circuit disposed between the input and output terminals of the transimpedance amplifier, said feedback circuit comprising:
• a transistor;
• a first current source supplying a first current to a first terminal of the transistor, said first current source being in communication with an input terminal of the transimpedance amplifier;
• a second current source receiving the first current from a second terminal of the transistor and supplying the received current to a voltage source;
• and
• a resistive load having a first terminal in communication with the second terminal of the transistor and a second terminal in communication with an output terminal of the transimpedance amplifier;
• said first and second terminals of the resistive load having DC voltages characterized substantially by a same value, said transistor being maintained in an active region of operation.