Patent ID: 7898268
Filing Date: 2011-03-01
Classification: G01R

Abstract:
1. A method for measuring the effective series resistance of a capacitor having a capacitor voltage, the method comprising: amplifying the capacitor voltage, prior to discharging, with an AC coupled amplifier yielding a first amplified signal representative substantially of offsets present in the AC coupled amplifier; storing a first measurement value output by the amplifier in a hold capacitor, the voltage across the hold capacitor representing the first measurement value; discharging the capacitor with a constant current for a measurement time substantially equal to a settling time associated with switching in of a current source providing the constant current thus causing a voltage swing of the capacitor voltage due substantially to a voltage drop across the effective series resistance; amplifying the capacitor voltage with the AC coupled amplifier yielding a second amplified signal being representative substantially of the voltage swing and the offsets; storing the second measurement value output by the amplifier in a hold capacitor, the voltage across the hold capacitor representing the second measurement value; and calculating the effective series resistance from the first and the second amplified signals, wherein subtracting the first measurement value from the second measurement value yields a difference proportional to the voltage drop across the effective series resistance of the capacitor.