Adc Dsl Systems, Inc.

Juan A Espinoza

L Grant Giddens

Clark Wayne Tollerson

Testing an oscillator and other electronic devices on a circuit board. One method of the present invention comprises powering the oscillator. Providing test instructions to a microprocessor on the circuit board to place the microprocessor in a test mode. Receiving a clock signal from the oscillator at a multiplexer in a field programmable gate array. Receiving operating instructions at the multiplexer from the microprocessor. Multiplexing the clock signal to an external access port with the multiplexer in response to the operating instructions and measuring the frequency of the clock signal at the external access port.

In-system testing of an oscillator

Testing of analog-to-digital and digital-to-analog converters formed in integrated circuits. In one embodiment, a method of testing an analog-to-digital (A/D) converter comprises applying an analog test signal of a first frequency to an input of the A/D converter. Sampling digital byte samples from an output of the A/D converter at a second sampling frequency and comparing select digital byte samples with each other. When the select digital byte samples match, storing a verify bit in a memory to verify the A/D converter is working. In another embodiment, a method of testing a digital-to-analog (D/A) comprises creating repeating digital byte samples with a logic circuit formed in the integrated circuit. Converting the repeating digital byte samples into an analog test signal with the D/A converter. Comparing the frequency of the analog test signal with the frequency of an expected analog signal to determine if the D/A converter is working.

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Wake Forest, NC, United States of America

Juan A Espinoza