Patent ID: 9503039
Filing Date: 2016-11-22
CPC Classification: G01R,H03F

Claim Text:
1. A method for adjusting a current sense (CS) amplifier, increasing a common mode rejection ratio (CMRR) and reducing a gain error of the CS amplifier as compared to an unadjusted CS amplifier, the method comprising: measuring a first referred to input (RTI) offset voltage while presenting a given common mode (CM) input voltage to both an inverting input and a non-inverting input of the CS amplifier; adding a first trim resistor of a plurality of selectable trim resistors within an adjustable feedback resistor chain to a feedback electrical path of the adjustable feedback resistor chain, said adjustable feedback resistor chain coupling an output of a differential amplifier within the CS amplifier to an inverting input of the differential amplifier; measuring, after adding the first trim resistor, a second RTI offset voltage while presenting the given CM input voltage to both the inverting input and the non-inverting input of the CS amplifier; estimating, based upon the first and second RTI offset voltages, a third RTI offset voltage value that would result by adding a second trim resistor of the plurality of selectable trim resistors to the feedback electrical path; using the first, second and third RTI offset voltage values to identify the combination of selectable trim resistors that achieves an RTI offset voltage closest to zero volts as compared to other combinations of selectable trim resistors; and adding the identified selectable trim resistors to the feedback electrical path.