Differential amplifier with adaptive biasing and offset cancellation

A differential amplifier comprising:

• a first electrical path comprising a first transistor and a first resistance element, where the first transistor is coupled to a current source and the first resistance element is coupled to a voltage source;
• a second electrical path comprising a second transistor and a second resistance element, where the second transistor is coupled to the current source and the second resistance element is coupled to the voltage source;
• a first adjustable current source, coupled between the voltage source and a first node located between the first transistor and the first resistance element, that provides a first biasing current for the first electrical path;
• and a second adjustable current source, coupled between the voltage source and a second node located between the second transistor and the second resistance element, that provides a second biasing current for the second electrical path,
• wherein at least one of the first current source and the second current source is provided by at least one biasing circuit, wherein the at least one biasing circuit comprises:
• a third electrical path coupled between the voltage source and a replica current source, wherein the third electrical path comprises at least one fifth transistor and a third resistance element where the at least one fifth transistor is coupled to the current source and the third resistance element is coupled to the voltage source;
• and
• a current digital-to-analog converter that provides a third biasing current for the third electrical path.

A method for amplifying signals, the method comprising:

• providing a first signal to a first input of a differential amplifier comprising two substantially matched electrical paths coupled between a voltage source and a current source;
• providing a second signal to a second input of the differential amplifier;
• isolating output nodes of the differential amplifier from the first and second inputs with two transistors that share a common gate bias;
• and
• compensating for current flows caused by the first signal and the second signal by providing biasing currents for the two electrical paths based on two adjustable current sources.

An apparatus for amplifying signals, the apparatus comprising:

• means for providing a first signal to a first input of a differential amplifier comprising two substantially matched electrical paths coupled between a voltage source and a current source;
• means for providing a second signal to a second input of the differential amplifier;
• means for isolating output nodes of the differential amplifier from the first and second inputs with two transistors that share a common gate bias;
• and
• means for compensating for current flows caused by the first signal and the second signal by providing biasing currents for the two electrical paths based on two adjustable current sources.