Patent ID: 7724014

Claim:
An integrated circuit comprising: (a) an ADC (analog to digital converter) having an analog input and a digital output; and (b) internal servo loop circuitry for use in conjunction with external servo loop circuitry and automatic test equipment to effectuate testing of the ADC, the internal servo loop circuitry including 1) a target code register having an input for receiving target codes from the automatic test equipment, 2) a digital comparator having a first input coupled to an output of the target code register, 3) test mode switch circuitry operative in response to the automatic test equipment during testing of the ADC to couple the digital output of the ADC to a second input of the digital comparator and to couple a target code from the automatic test equipment to the input of the target code register, and 4) the test mode switch circuitry being operative in response to the automatic test equipment during normal operation of the ADC to decouple the digital output of the ADC from the second input of the digital comparator and to connect the digital output of the ADC to a digital output port of the integrated circuit and to decouple the input of the target code register from the automatic test equipment, the external servo loop circuitry including an integrator operative in response to an output of the digital comparator to generate a ramping input signal on the analog input of the ADC during the testing, a voltmeter associated with the automatic test system being coupled to measure transition voltage values of the ramping analog input voltage during the testing.