METHOD OF TRIMMING CURRENT SOURCE USING ON-CHIP ADC

摘要

A method of trimming a current source in an IC includes deriving a reference voltage from an external supply, and developing a measurement voltage across an external reference resistance receiving the current to be trimmed. An on-chip ADC is used to provide corresponding digital reference and digital measurement signals. A digital comparator compares the digital signals and provides a digital trim signal, which is used to adjust the current to be trimmed until the digital measurement signal is equal to the digital reference signal within an acceptable tolerance. Gain and offset errors in the ADC cancel and do not affect the calibration of the trim operation.

主权项

1. An integrated circuit (IC), comprising:
a current source that is trimmed in a trimming mode of operation in which the current source is connected to pass a current through a reference resistance of a test board of a tester and provide a corresponding measurement voltage; a reference voltage source for providing a reference voltage that is derived from a supply voltage of the tester; an on-chip analog-to-digital converter (ADC) for converting the reference voltage and the measurement voltage to a corresponding digital reference signal and a digital measurement signal respectively; and a digital comparator for comparing the digital reference signal and the digital measurement signal, and providing a digital trim signal used to adjust the current from the current source until the digital measurement signal is equal to the digital reference signal, within an acceptable tolerance.