Techniques for pga linearity

A method for configuring an amplifier, the amplifier having differential input terminals and at least one output, the method comprising:

• selectively closing at least one feedback switch to couple a terminal of the at least one output to a terminal of the differential input via a corresponding series-coupled feedback resistance, a terminal of each feedback switch directly coupled to the terminal of the differential input;
• and
• selectively closing at least one input switch to couple a terminal of the differential input to a corresponding series-coupled input resistance, a terminal of each input switch directly coupled to the terminal of the differential input;
• wherein the ratio between the on-resistances of any two switches is configured to be substantially equal to the ratio of the corresponding series-coupled resistances to each other.

An apparatus comprising:

• an amplifier having at least one output and a differential input comprising positive and negative input terminals;
• means for coupling a terminal of the at least one output to a terminal of the differential input via a corresponding series-coupled feedback resistance;
• and
• means for coupling a terminal of the differential input to a corresponding series-coupled input resistance;
• wherein each of said means is configured to have an on-resistance at a fixed proportion relative to the corresponding series-coupled resistance.