Patent ID: 6211803
Filing Date: 2001-04-03
Classification: H03M

Abstract:
A test circuit for measuring a switching point voltage of an N-bit analog-to-digital converter (ADC) having an analog input and a digital output, the test circuit comprising:a digital comparator for comparing a digital output value from the digital output of the ADC to a predetermined digital value, and generating a first logic value when the digital output value is less than the predetermined value, and a second logic value when the digital output value is equal to or greater than the predetermined value;an analog averaging circuit for averaging voltages of the first and second digital logic values, and providing an analog average value to the analog input of the ADC such that the analog input of the ADC receives no external analog input signal during the measurement; anda digital averaging circuit for averaging the first and second digital logic values, and generating a digital average value which is representative of the switching point voltage.